Peristaltic pump

ABSTRACT

A peristaltic pump having at least first, second, and third stages is provided. The peristaltic pump includes a plunger, inlet and outlet valves, a spring, and an actuator. The plunger actuates toward and away from a tube, the inlet valve is upstream of the plunger, the outlet valve is downstream of the plunger, the spring biases the plunger toward the tube, and the actuator mechanically engages and disengages from the plunger. In the first stage, the inlet valve is opened and the plunger is actuated from the tube, in the second stage, the inlet valve is closed, the plunger is actuated toward the tube, and the actuator is mechanically disengaged from the plunger, and in the third stage, the outlet valve is opened. In the third stage or in a fourth stage, the actuator actuates the plunger toward the tube to discharge fluid downstream past the outlet valve.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 14/873,515, filed Oct. 2, 2015 and entitled System,Method and Apparatus for Infusing Fluid, now U.S. Publication No.US-2016-0097382-A1, published Apr. 7, 2016 (Attorney Docket No. Q68),which is a Continuation Application of U.S. patent application Ser. No.13/725,790, filed Dec. 21, 2012 and entitled System, Method andApparatus for Infusing Fluid, now U.S. Pat. No. 9,677,555, Issued Jun.13, 2017 (Attorney Docket No. J76), which claims priority to and thebenefit of the following:

U.S. Provisional Patent Application Ser. No. 61/578,649, filed Dec. 21,2011 and entitled System, Method, and Apparatus for Infusing Fluid(Attorney Docket No. J02);

U.S. Provisional Patent Application Ser. No. 61/578,658, filed Dec. 21,2011 and entitled System, Method, and Apparatus for Estimating LiquidDelivery (Attorney Docket No. J04);

U.S. Provisional Patent Application Ser. No. 61/578,674, filed Dec. 21,2011 and entitled System, Method, and Apparatus for Dispensing OralMedications (Attorney Docket No. J05);

U.S. Provisional Patent Application Ser. No. 61/679,117, filed Aug. 3,2012 and entitled System, Method, and Apparatus for Monitoring,Regulating, or Controlling Fluid Flow (Attorney Docket No. J30); and

U.S. Provisional Patent Application Ser. No. 61/651,322, filed May 24,2012 and entitled System, Method, and Apparatus for Electronic PatientCare (Attorney Docket No. J46), each of which is hereby incorporatedherein by reference in its entirety.

U.S. patent application Ser. No. 13/725,790, filed Dec. 21, 2012 andentitled System, Method and Apparatus for Infusing Fluid, now U.S. Pat.No. 9,677,555, Issued Jun. 13, 2017 (Attorney Docket No. J76), is also aContinuation-In-Part Application of the following:

U.S. patent application Ser. No. 13/333,574, filed Dec. 21, 2011 andentitled System, Method, and Apparatus for Electronic Patient Care, nowU.S. Publication No. US-2012-0185267-A1, published Jul. 19, 2012(Attorney Docket No. 197), and

PCT Application Serial No. PCT/US11/66588, filed Dec. 21, 2011 andentitled System, Method, and Apparatus for Electronic Patient Care(Attorney Docket No. I97WO), both of which are hereby incorporatedherein by reference in their entireties.

U.S. patent application Ser. No. 14/873,515 (Attorney Docket No. Q68),is also a Continuation-In-Part Application of the following:

U.S. patent application Ser. No. 13/723,238, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Clamping, now U.S. Pat. No.9,759,369, Issued Sep. 12, 2017 (Attorney Docket No. J47);

U.S. patent application Ser. No. 13/723,235, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Dispensing Oral Medications,now U.S. Pat. No. 9,400,873, Issued Jul. 26, 2016 (Attorney Docket No.J74);

U.S. patent application Ser. No. 13/724,568, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Estimating Liquid Delivery,now U.S. Pat. No. 9,295,778, Issued Mar. 29, 2016 (Attorney Docket No.J75);

U.S. patent application Ser. No. 13/723,239, filed Dec. 21, 2012, andentitled System, Method, and Apparatus for Electronic Patient Care, nowU.S. Publication No. US-2013-0297330-A1, published Nov. 7, 2013(Attorney Docket No. J77);

U.S. patent application Ser. No. 13/723,242, filed Dec. 21, 2012, andentitled System, Method, and Apparatus for Electronic Patient Care, nowU.S. Publication No. US-2013-0317753-A1, published Nov. 28, 2013(Attorney Docket No. J78);

U.S. patent application Ser. No. 13/723,244, filed Dec. 21, 2012, andentitled System, Method, and Apparatus for Monitoring, Regulating, orControlling Fluid Flow, now U.S. Pat. No. 9,151,646, Issued Oct. 6, 2015(Attorney Docket No. J79);

U.S. patent application Ser. No. 13/723,251, filed Dec. 21, 2012, andentitled System, Method, and Apparatus for Estimating Liquid Delivery,now U.S. Pat. No. 9,636,455, Issued May 2, 2017 (Attorney Docket No.J81); and

U.S. patent application Ser. No. 13/723,253, filed Dec. 21, 2012, andentitled System, Method, and Apparatus for Electronic Patient Care, nowU.S. Publication No. US-2013-0191513-A1, published Jul. 25, 2013(Attorney Docket No. J85).

U.S. patent application Ser. No. 14/873,515 (Attorney Docket No. Q68),may also be related to one or more of the following U.S. patentapplications filed on even date herewith, all of which are herebyincorporated herein by reference in their entireties:

PCT Application Serial No. PCT/US12/71131, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Dispensing Oral Medications(Attorney Docket No. J74WO);

PCT Application Serial No. PCT/US12/71490, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Infusing Fluid (AttorneyDocket No. J76WO);

PCT Application Serial No. PCT/US12/71142, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Monitoring, Regulating, orControlling Fluid Flow (Attorney Docket No. J79WO); and

PCT Application Serial No. PCT/US12/71112, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Estimating Liquid Delivery(Attorney Docket No. J81 WO).

BACKGROUND Relevant Field

The present disclosure relates to infusing fluid. More particularly, thepresent disclosure relates to a system, method and apparatus forinfusing fluid into a patient, e.g., using a pump.

Description of Related Art

Providing patient care in a hospital generally necessitates theinteraction of numerous professionals and caregivers (e.g., doctors,nurses, pharmacists, technicians, nurse practitioners, etc.) and anynumber of medical devices/systems needed for treatment of a givenpatient. Despite the existence of systems intended to facilitate thecare process, such as those incorporating electronic medical records(“EMR”) and computerized provider order entry (“CPOE”), the process ofproviding comprehensive care to patients including ordering anddelivering medical treatments, such as medications, is associated with anumber of non-trivial issues.

Peristaltic pumps are used in a variety of applications such as medicalapplications, especially fluid transfer applications that would benefitfrom isolation of fluid from the system and other fluids. Someperistaltic pumps work by compressing or squeezing a length of flexibletubing. A mechanical mechanism pinches a portion of the tubing andpushes any fluid trapped in the tubing in the direction of rotation.There are rotary peristaltic pumps and finger peristaltic pumps.

Rotary peristaltic pumps typically move liquids through flexible tubingplaced in an arc-shaped raceway. Rotary peristaltic pumps are generallymade of two to four rollers placed on a roller carrier drivenrotationally by a motor. A typical rotary peristaltic pump has a rotorassembly with pinch rollers that apply pressure to the flexible tubingat spaced locations to provide a squeezing action on the tubing againstan occlusion bed. The occlusion of the tubing creates increased pressureahead of the squeezed area and reduced pressure behind that area,thereby forcing a liquid through the tubing as the rotor assembly movesthe pinch rollers along the tubing. In order to operate, there mustalways be an occlusion zone; in other words, at least one of the rollersis always pressing on the tube.

Finger peristaltic pumps are made of a series of fingers moving incyclical fashion to flatten a flexible tube against a counter surface.The fingers move essentially vertically, in wave-like fashion, forming azone of occlusion that moves from upstream to downstream. The lastfinger—the furthest downstream—raises up when the first finger—thefurthest upstream—presses against the counter surface. The most commonlyused finger pumps are linear, meaning that the counter surface is flatand the fingers are parallel. In this case, the fingers are controlledby a series of cams arranged one behind another, each cam cooperatingwith a finger. These cams are placed helically offset on a shared shaftdriven rotationally by a motor. There are also rotary-finger peristalticpumps, which attempt to combine the advantages of roller pumps withthose of finger pumps. In this type of pump, the counter surface is notflat, but arc-shaped, and the fingers are arranged radially inside thecounter surface. In this case, a shared cam with multiple knobs placedin the center of the arc is used to activate the fingers.

SUMMARY

A peristaltic pump, and related system method are provided. Theperistaltic pump includes a cam shaft, first and second pinch-valvecams, first and second pinch-valve cam followers, a plunger cam, aplunger-cam follower, a tube receiver, and a spring-biased plunger. Thefirst and second pinch-valve cams are coupled to the cam shaft. Thefirst and second pinch-valve cam followers each engage the first andsecond pinch-valve cams, respectively. The plunger cam is coupled to thecam shaft. The plunger-cam follower engages the plunger cam. The tubereceiver is configured to receive a tube. The spring-biased plunger iscoupled to the plunger-cam follower such that the expansion of theplunger cam along a radial angle intersecting the plunger-cam followeras the cam shaft rotates pushes the plunger cam follower towards theplunger and thereby disengages the spring-biased plunger from the tube.A spring coupled to the spring-biased plunger biases the spring-biasedplunger to apply the crushing force to the tube.

In some embodiments, a slide occluder includes an RFID tag and theinfusion pump includes an RFID interrogator. A processor associated with(or in) the infusion pump interrogates the RFID tag to determine if theslide occluder is authorized for use. For example, the RFID tag may havean encryption key and/or authorized identification value.

In some embodiments, a cam profile for an infusion pump may be shapedsuch that rotation in any direction causes forward flow.

In some embodiments, an infusion pump may include a downstream occluderto create a smooth fluid flow to the patient.

In some embodiments, the infusion pump may automatically prime, e.g.,the tube may have an RFID tag and/or a barcode that may be read by thepump, which the pump uses to estimate a priming volume of the downstreamtube automatically (for fluid flow estimation, etc.)

In some embodiments, an infusion pump includes a resistive element thatis compressed against a tube. The infusion pump estimates the fluidpressure in accordance with the resistance.

In some embodiments, the infusion pump includes a temperature sensor toestimate the temperature of the fluid within the tube. The infusion pumpmay correct for the temperature of the tube and/or fluid in its fluidflow calculation (e.g., the delta fluid estimation described below).

In some embodiments, a display on a pump UI will display instructionshow to install the slide occluder (e.g., when the ID in an RFID tag inan occluder is an unauthorized ID, for example).

In some embodiments, an electronics module is attachable to an infusionpump to control the pump. The electronics module may include an RFtransceiver, a battery, and a control component.

In some embodiment of the present disclosure, a peristaltic pumpincludes a cam shaft, first and second pinch-valve cams, first andsecond pinch-valve cam followers, a plunger cam, a plunger-cam follower,a tube receiver, a spring-biased plunger, a position sensor, and aprocessor. The first and second pinch-valve cams are operatively coupledto the cam shaft. The first and second pinch-valve cam followers areconfigured to engage the first and second pinch-valve cams. The plungercam is coupled to the cam shaft. The plunger-cam follower is configuredto engage the plunger cam. The tube receiver is configured to receive atube. The spring-biased plunger is coupled to the plunger-cam followersuch that expansion of the plunger cam along a radial angle intersectingthe plunger-cam follower as the cam shaft rotates pushes the plunger camto disengage the spring-biased plunger from the tube. A spring iscoupled to the spring-biased plunger to bias the spring-biased plungerto apply the crushing force to the tube. The position sensor isoperatively coupled to the spring-biased plunger configured to determinea position of the spring-biased plunger. The processor is coupled to theposition sensor and is configured to estimate fluid flow of fluid withinthe tube utilizing the position using the position sensor.

The pump may include an angle sensor operatively coupled to the camshaft configured to determine an angle of rotation of the cam shaft.

The processor determines the first static region by identifying a peakmovement of the plunger as measured by the position sensor andidentifies the second static region to be after the identified peak. Theprocessor may determine the first static region by identifying the firststatic region within a predetermined range of angles as indicated by theangle sensor. The processor may determine the second static region byidentifying the second static region within a second predetermined rangeof angles as indicated by the angle sensor. The processor may determinethe first and second static regions by measuring position sensor atpredetermined angles as indicated by the angle sensor.

The processor may compare a first static region measured by the positionsensor to a second static region measured by the position sensor toestimate the fluid flow. The processor may determine the first staticregion by identifying a peak of the movement of the position sensor andidentifying the first static region after the identified peak. Theprocessor may determine the second static region by identifying an endof the first static region.

In some embodiments, the pump also includes a balancer cam, abalancer-cam follower, and a balancer spring configured to apply a forceagainst the balancer-cam follower and thereby apply a force from thebalancer-cam follower to the balancer cam. The balancer cam may beshaped to reduce a peak torque of the cam shaft as the cam shaft rotatesaround its axis of rotation.

The pump may also include an electric motor operatively coupled to thecam shaft to apply a rotational torque to the cam shaft. The electricmotor may be a stepper motor, a DC motor, a brushless DC motor, abrushed DC motor, an AC motor, a polyphase induction motor, an electricmotor with at least one permanent magnet coupled to a stator or a rotor,and an induction motor.

In another embodiment of the present disclosure, a pump includes: afirst layer; and a second layer at least partially disposed adjacent tothe first layer defining an inlet fluid path, a bubble chamber, and anoutlet fluid path. The inlet fluid path is in fluid communication withthe bubble chamber and the outlet fluid path is in fluid communicationwith the bubble chamber. The pump also includes an assembly having avariable-volume chamber, a reference chamber, and an acoustic port inoperative communication with the variable-volume and reference chamberssuch that the variable-volume chamber includes an opening disposedaround the bubble chamber on at least one of the first and a secondlayers.

The pump may include a plunger positioned to engage the bubble chamber.

The pump may include source of pressure and a fluid port coupled to thereference chamber such that the source of pressure is in fluidcommunication with the fluid port to apply at least one of a negativepressure and a positive pressure thereto.

In some embodiments, the pump also includes: (1) a reference speakerdisposed within the reference chamber; a reference microphone disposedwithin the reference chamber; and a variable-volume microphone disposedwithin the variable-volume chamber.

The pump may include a processor in operative communication with thereference speaker, and the reference and variable-volume microphones.The processor may be configured to control the speaker to generate aplurality of frequencies and sense the frequencies through the referenceand variable-volume microphones to estimate a volume of the variablevolume using the sensed frequencies from the reference andvariable-volume microphones. The processor may be further configured toestimate a flow rate of the pump using the estimated volume of thevariable volume.

In another embodiment of the present disclosure, a flow rate meterincludes: (1) a first layer; (2) a second layer at least partiallydisposed adjacent to the first layer defining an inlet fluid path, abubble chamber, and an outlet fluid path, wherein the inlet fluid pathis in fluid communication with the bubble chamber and the outlet fluidpath is in fluid communication with the bubble chamber; (3) an assemblyhaving a variable-volume chamber, a reference chamber, and an acousticport in operative communication with the variable-volume and referencechambers, wherein the variable-volume chamber includes an openingdisposed around the bubble chamber on at least one of the first and asecond layers; (4) a reference speaker disposed within the referencechamber; (5) a reference microphone disposed within the referencechamber; (6) a variable-volume microphone disposed within thevariable-volume chamber; and (7) a processor in operative communicationwith the reference speaker, and the reference and variable-volumemicrophones. The processor is configured to control the speaker togenerate a plurality of frequencies and sense the frequencies throughthe reference and variable-volume microphones. The processor is furtherconfigured to estimate a volume of the variable volume using the sensedfrequencies from the reference and variable-volume microphones. Theprocessor is further configured to estimate a flow rate using theestimated volume of the variable volume.

In yet another embodiment of the present disclosure, a peristaltic pumpincludes a housing a motor, a cam shaft, a plunger, a pivot shaft, aplunger, a bias member, a position sensor, and a processor. The camshaft is operatively coupled to the motor such that rotation of themotor rotates the cam shaft. The plunger cam is coupled to the cam shaftfor rotation therewith. The pivot shaft is operatively coupled to thehousing. The plunger is pivotally coupled to the pivot shaft, theplunger having a cam follower configured to engage the plunger cam ofthe cam shaft. The plunger is configured to pivot to a first position tocompress a tube and to a second position away from the tube. The biasmember is configured to bias the plunger to the first position tocompress the tube. The position sensor coupled to the plunger to measurea position of the plunger. The processor is coupled to the positionsensor to estimate a volume of fluid discharged from the tube when thebias member causes the plunger to move towards the first position.

The plunger and plunger cam may be configured to compress the tube usingonly a force of the bias member. The plunger cam may be configured toonly retract the plunger to the second position. The plunger may beconfigured to engage the plunger cam such that the plunger cam does notforce the plunger against the tube. The plunger may be any suitableshape, such as an L-shape or a U-shape, among other shapes.

The pump may further include an inlet valve and an outlet valve. Theinlet valve, the outlet valve, the plunger and the plunger cam may beconfigured to compress the tube while the inlet and outlet valves areclosed such that the processor can measure a first position of theplunger using the position sensor. The inlet valve, the outlet valve,the plunger and the plunger cam may be configured to open the outletvalve after the first position of the plunger is measured to dischargefluid out of the tube through the outlet valve. The processor may beconfigured to measure a second position of the plunger using theposition sensor after the outlet valve is opened. The processor maycompare the first measured position to the second measured position todetermine an amount of fluid discharged through the outlet valve. Theinlet valve and the outlet value may be spring biased against the tube.

The inlet valve may include an inlet-valve cam follower configured tointerface an inlet-valve cam coupled to the cam shaft. The outlet valvemay include an outlet-valve cam follower configured to interface anoutlet-valve cam coupled to the cam shaft.

In another embodiment of the present disclosure, a pump includes ahousing, a door, a carrier, and a lever. The housing has a first slot.The door is pivotally coupled to the housing and has a platen configuredto receive a tube. The door is configured to have a closed position andan open position. The door includes a second slot. The carrier has apivot defining first and second portions pivotally coupled together. Thefirst portion is slidingly disposed within the first slot of thehousing, and the second portion is slidingly disposed within the secondslot of door. The lever handle is pivotally coupled to the door and isoperatively coupled to the carrier.

In some embodiments, when the door is open, the first portion of thecarrier is disposed within the first slot and the second portion of thecarrier is disposed within the second slot, and the first and secondportions of the carrier are disposed orthogonal to each other away froma pivot point when the door is open.

The peristaltic pump may be configured such that when the door is shut,the first and second portions of the carrier are positioned adjacent toeach other such that the carrier is slidable within the first and secondslots as the lever handle moves.

The second portion may be configured to receive a slide occluder coupledto the tube in the occluded position when the door is in the openposition. The door and lever handle may be configured such that when thedoor is in the closed position, movement of the lever handle moves thefirst and second portions of the carrier towards the first slot tothereby move the slide occluder into the unoccluded position.

In some embodiments, a plunger is configured to compress the tube in theplaten when the door is closed. The lever handle is operatively coupledto the plunger to lift the plunger away from the tube when the leverhandle is in an open position and to actuate the plunger towards thetube when the lever handle is in a closed position.

The second portion may be configured to receive a slide occluder coupledto the tube in the occluded position when the door is in the openposition. In some embodiments, the door may includes a leaf spring suchthat the door is configured to latch onto the housing when the door isin the closed position and the lever handle is pivoted against the doorsuch that the leaf spring compresses the door against the housing.

In some additional embodiment, a pump includes: (1) a motor means forrotating; (2) a cam means coupled to the motor means for rotating; (3) aplunger means for compressing against a tube; and (4) a volumemeasurement means for estimating a volume of fluid discharged throughthe tube.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects will become more apparent from the followingdetailed description of the various embodiments of the presentdisclosure with reference to the drawings wherein:

FIG. 1 shows block diagram of a system for infusing liquid in accordancewith an embodiment of the present disclosure;

FIG. 2 shows a block diagram of an infusion site monitor of the systemof FIG. 1 in accordance with an embodiment of the present disclosure;

FIG. 3 shows a block diagram of a pump for infusing liquid of the systemof FIG. 1 in accordance with an embodiment of the present disclosure;

FIG. 4 shows a drip-chamber holder receiving a drip chamber, and thedrip-chamber holder includes a flow meter and a free-flow detector inaccordance with an embodiment of the present disclosure;

FIG. 5 shows the drip-chamber holder of FIG. 4 with the door open inaccordance with an embodiment of the present disclosure;

FIG. 6 shows a block diagram of another drip-chamber holder inaccordance with another embodiment of the present disclosure;

FIG. 7 shows a ray diagram illustrating the diameter of a blur circle toillustrate aspects of the cameras of the drip-chamber holder of FIGS. 4and 5 in accordance with an embodiment of the present disclosure;

FIG. 8 is a graphic illustrating the blur circle as calculated for avariety of lens-to-focal plane separations and lens-to-image separationsfor the cameras of the drip-chamber holder of FIGS. 4 and 5 inaccordance with an embodiment of the present disclosure;

FIG. 9 is a graphic illustrating the blur circle divided by pixel sizewhen a 20 millimeter focal length lens of the cameras of thedrip-chamber holder of FIGS. 4 and 5 is used in accordance with anembodiment of the present disclosure;

FIG. 10 is a graphic illustrating the blur circle divided by pixel sizewhen a 40 millimeter focal length lens of the cameras of thedrip-chamber holder of FIGS. 4 and 5 is used in accordance with anembodiment of the present disclosure;

FIG. 11 shows a table illustrating the corresponding fields of viewabout the optical axis for the corners of the two configurations ofFIGS. 9 and 10 in accordance with an embodiment of the presentdisclosure;

FIG. 12 is a block diagram of an imaging system of the cameras of thedrip-chamber holder of FIGS. 4 and 5 in accordance with an embodiment ofthe present disclosure;

FIG. 13 is a graphic illustration of an image captured by the camera ofthe system of FIG. 12 in accordance with an embodiment of the presentdisclosure;

FIG. 14 is a block diagram of an imaging system of the cameras of thedrip-chamber holder of FIGS. 4 and 5 in accordance with an embodiment ofthe present disclosure;

FIG. 15 is a graphic illustration of an image captured by the camera ofFIG. 14 when a free flow condition exists in accordance with anembodiment of the present disclosure;

FIG. 16 is a graphic illustration of an image captured by the camera ofFIG. 14 for use as a background image in accordance with an embodimentof the present disclosure;

FIG. 17 is a graphic illustration of an image captured by the camerawhen drops are being formed within the drip chamber of FIG. 14 inaccordance with an embodiment of the present disclosure;

FIG. 18 is a graphic illustration of an image captured by the camera ofFIG. 14 for use as a background image in accordance with an embodimentof the present disclosure;

FIG. 19 is a graphic illustration of a difference between the images ofFIGS. 17 and 18 with additional processing in accordance with anembodiment of the present disclosure;

FIG. 20 is a graphic representation of the image processing performedusing FIGS. 17-19 to determine if a free flow condition exists inaccordance with an embodiment of the present disclosure;

FIG. 21 is a graphic illustration of an image captured by the camerawhen a free flow condition exists thereby forming a stream within thedrip chamber of FIG. 14 in accordance with an embodiment of the presentdisclosure;

FIG. 22 is a graphic illustration of an image captured by the camera ofFIG. 14 for use as a background image in accordance with an embodimentof the present disclosure;

FIG. 23 is a graphic illustration of a difference between the images ofFIGS. 20 and 21 with some additional processing for use in detecting afree flow condition in accordance with an embodiment of the presentdisclosure;

FIG. 24 is a graphic representation of the image processing performedusing FIGS. 21-23 to determine if a free flow condition exists inaccordance with an embodiment of the present disclosure;

FIG. 25 illustrates a template for pattern matching to determine if afree flow condition exits using FIGS. 17-19 or FIGS. 21-23 in accordancewith an embodiment of the present disclosure;

FIG. 26 is a graphic illustration of a difference between a referenceimage and an image containing a steam processed with edge detection andline detection for use in detecting a free flow condition in accordancewith an embodiment of the present disclosure;

FIG. 27 is a graphic illustration of an image captured by the camerawhen a free flow condition exists thereby forming a stream within thedrip chamber of FIG. 14 in accordance with an embodiment of the presentdisclosure;

FIG. 28 is a block diagram of an imaging system for use with thedrip-chamber holder of FIGS. 4-5 or FIG. 6 having a back pattern withstripes and a light source shining on the stripes from an adjacentlocation to a camera in accordance with an embodiment of the presentdisclosure;

FIG. 29 is a block diagram of an imaging system for use with thedrip-chamber holder of FIGS. 4-5 or FIG. 6 having a back pattern withstripes and a light source shining on the stripes from behind the backpattern relative to an opposite end to a camera in accordance with anembodiment of the present disclosure;

FIG. 30 shows an image from the camera of FIG. 29 when a drop distortsthe back pattern of FIG. 26 in accordance with an embodiment of thepresent disclosure;

FIG. 31 is a block diagram of an imaging system for use with thedrip-chamber holder of FIGS. 4-5 or FIG. 6 having a back pattern with acheckerboard pattern and a light source shining on the stripes frombehind the back pattern relative to an opposite end to a camera inaccordance with an embodiment of the present disclosure;

FIG. 32 shows an image from the camera of FIG. 31 when a drop distortsthe back pattern of FIG. 26 in accordance with an embodiment of thepresent disclosure;

FIG. 33 shows a block diagram of an air detector using a camera inaccordance with an embodiment of the present disclosure;

FIG. 34 shows a matching template for use in air detection in accordancewith an embodiment of the present disclosure;

FIG. 35 illustrates an image captured by the camera of system of FIG. 33for detecting that no tube is within a cavity in accordance with anembodiment of the present disclosure;

FIG. 36 illustrates an image captured by the camera of the system ofFIG. 33 for detecting air bubbles in accordance with an embodiment ofthe present disclosure;

FIG. 37 illustrates an image captured by the camera of the system ofFIG. 33 for detecting blood in accordance with an embodiment of thepresent disclosure;

FIG. 38 illustrates the image of FIG. 37 that has undergone imageprocessing for detecting a threshold amount of red for detecting bloodin accordance with an embodiment of the present disclosure;

FIG. 39 shows an infiltration detector in accordance with an embodimentof the present disclosure;

FIG. 40 shows a graphic illustrating the optical absorption ofoxygenated and de-oxygenated hemoglobin in accordance with an embodimentof the present disclosure;

FIG. 41 shows another infiltration detector in accordance with anotherembodiment of the present disclosure;

FIG. 42 shows a perspective view of an occluder in accordance to anembodiment of the present disclosure;

FIG. 43 shows a side view of the occluder of FIG. 42 in accordance to anembodiment of the present disclosure;

FIG. 44 shows a side view of the occluder of FIG. 42 in operation inaccordance to an embodiment of the present disclosure;

FIG. 45 shows a side view of a valve for use in a cassette in accordancewith an embodiment of the present disclosure;

FIG. 46 shows a top view of the valve of FIG. 45 in accordance with anembodiment of the present disclosure;

FIG. 47 shows another side view of the valve of FIG. 45 installed withina cassette in accordance with an embodiment of the present disclosure;

FIG. 48 shows a sliding valve having an inclined plane to providesealing in accordance with an embodiment of the present disclosure;

FIG. 49 shows a side view of the sliding valve of FIG. 48 in accordancewith an embodiment of the present disclosure;

FIG. 50 shows the mount of the sliding valve of FIGS. 48-49 inaccordance with an embodiment of the present disclosure;

FIGS. 51-55 show a vent for a reservoir in accordance with an embodimentof the present disclosure;

FIGS. 56-58 illustrate the stages of a flow meter in accordance with anembodiment of the present disclosure;

FIG. 59 shows a diagram of a disposable portion of a flow meter inaccordance with an embodiment of the present disclosure;

FIGS. 60-62 show several views of a single-sided disposable portion of aflow meter in accordance with an embodiment of the present disclosure;

FIGS. 63-65 show several views of a double-sided disposable portion of aflow meter in accordance with an embodiment of the present disclosure;

FIGS. 66-68 show several views of a three-layer, opposite-sided,disposable portion of a flow meter in accordance with an embodiment ofthe present disclosure;

FIG. 69 shows a top view of another disposable portion of a flow meterin accordance with another embodiment of the present disclosure;

FIG. 70 shows a flow rate meter including a full acoustic volume sensing(“AVS”) clam shell assembly and a single-sided disposable portion inaccordance with an embodiment of the present disclosure;

FIG. 71 shows a side view of flow rate meter including a double-sidedAVS assembly with integral perimeter seal valves in accordance with anembodiment of the present disclosure;

FIG. 72 shows a side view of another flow rate meter including asingle-sided AVS assembly with surrounding AVS chambers in accordancewith another embodiment of the present disclosure;

FIG. 73 shows a side view of yet another flow rate meter including twopiston valves in accordance with another embodiment of the presentdisclosure;

FIG. 74 shows a flow rate meter having top and bottom AVS assemblieswhich provide a semi-continuous flow in accordance with an embodiment ofthe present disclosure;

FIG. 75 shows a flow rate meter having two in-line AVS assemblies inaccordance with an embodiment of the present disclosure;

FIG. 76 shows a membrane pump having a negative pressure source inaccordance with an embodiment of the present disclosure;

FIG. 77 shows a membrane pump having negative and positive pressuresources in accordance with an embodiment of the present disclosure;

FIG. 78 shows a optical-sensor based flow rate meter in accordance withan embodiment of the present disclosure;

FIG. 79 shows a pressure-controlled membrane pump in accordance with anembodiment of the present disclosure;

FIGS. 80-82 show a diagram of a legend for use in conjunction with FIGS.79 and 83-98 in accordance with an embodiment of the present disclosure;

FIG. 83 shows a flow-controlled membrane pump in accordance with anembodiment of the present disclosure;

FIG. 84 shows a state diagram of the operation of the flow-controlledmembrane pump of FIG. 83 in accordance with an embodiment of the presentdisclosure;

FIG. 85 shows the flow-controlled membrane pump of FIG. 83 illustratingthe operation of the valves when in the Idle state of the state diagramof FIG. 84 in accordance with an embodiment of the present disclosure;

FIG. 86 shows a more detailed view of the idle state of the statediagram of FIG. 84 in accordance with an embodiment of the presentdisclosure;

FIGS. 87-88 show the flow-controlled membrane pump of FIG. 83 in useduring the positive pressure valve leak test state of FIG. 84 inaccordance with an embodiment of the present disclosure;

FIG. 89 shows a more detailed view of the positive pressure valve leaktest state of FIG. 84 in accordance with an embodiment of the presentdisclosure;

FIGS. 90-91 show the flow-controlled membrane pump of FIG. 83 in useduring the negative pressure valve leak test state of FIG. 84 inaccordance with an embodiment of the present disclosure;

FIG. 92 shows a more detailed view of the negative pressure valve leaktest state of FIG. 84 in accordance with an embodiment of the presentdisclosure;

FIG. 93 shows the flow-controlled membrane pump of FIG. 83 in use duringthe fill state of FIG. 84 in accordance with an embodiment of thepresent disclosure;

FIG. 94 shows a more detailed view of the fill state of FIG. 84 inaccordance with an embodiment of the present disclosure;

FIG. 95 shows the flow-controlled membrane pump of FIG. 83 in use duringan AVS measurement in accordance with an embodiment of the presentdisclosure;

FIG. 96 shows a more detailed view of the AVS measurement state of FIG.84 in accordance with an embodiment of the present disclosure;

FIG. 97 shows the flow-controlled membrane pump of FIG. 83 in use duringthe emptying state of FIG. 84 in accordance with an embodiment of thepresent disclosure;

FIG. 98 shows a more detailed view of the emptying state of FIG. 84 inaccordance with an embodiment of the present disclosure;

FIG. 99 shows a membrane pump having an elastic membrane that is flushwith a disposable portion and applies a force to a liquid in accordancewith an embodiment of the present disclosure;

FIGS. 100-101 show two embodiments of lung pumps in accordance withembodiments of the present disclosure;

FIGS. 102-104 show several gaskets for sealing a lung pump in accordancewith additional embodiments of the present disclosure;

FIG. 105 shows another lung pump in accordance with another embodimentof the present disclosure;

FIGS. 106-112 illustrate the operation of a piston pump while performingvarious checks in accordance with an embodiment of the presentdisclosure;

FIGS. 113 and 114 illustrate a piston pump in accordance with anotherembodiment of the present disclosure;

FIGS. 115 and 116 show two views of a cassette having several membranepumps of FIGS. 113 and 114 in accordance with an embodiment of thepresent disclosure;

FIG. 117 shows a cassette having a membrane pump and volcano valves inaccordance with an embodiment of the present disclosure;

FIG. 118 shows a roller mechanism of a cassette-based pump in accordancewith an embodiment of the present disclosure;

FIG. 119 shows the fluid paths of a cassette-based pump for use with theroller mechanism of FIG. 118 in accordance with an embodiment of thepresent disclosure;

FIG. 120 shows the fluid paths of a cassette-based pump for use with theroller mechanism of FIG. 118 in accordance with an embodiment of thepresent disclosure;

FIG. 121 shows the stages of an infiltration test using a roller inaccordance with an embodiment of the present disclosure;

FIG. 122 shows the stages of an infiltration test using a piston inaccordance with an embodiment of the present disclosure;

FIGS. 123 and 124 show a cell-base reservoir in accordance with anembodiment of the present disclosure;

FIGS. 125 and 126 show a tube-based reservoir in accordance with anembodiment of the present disclosure;

FIG. 127 shows several stages illustrating a method for operating aplunger pump in conjunction with an AVS assembly in accordance with anembodiment of the present disclosure;

FIG. 128 shows several stages illustrating a method for operating aplunger pump in conjunction with an AVS assembly in accordance withanother embodiment of the present disclosure;

FIG. 129 shows several stages illustrating a method for using a plungerpump having an AVS assembly in accordance with an embodiment of thepresent disclosure;

FIG. 130 shows several stages illustrating a method for using a plungerpump having an AVS assembly in accordance with an embodiment of thepresent disclosure;

FIG. 131 shows several stages illustrating a method for using a plungerpump having an AVS assembly in accordance with an embodiment of thepresent disclosure;

FIG. 132 shows a plunger pump with an actuator inside the variablevolume for use with a standard IV set tubing in accordance with anembodiment of the present disclosure;

FIG. 133 shows several views of a cam-driven linear peristaltic pumphaving pinch valves and a plunger inside a variable volume in accordancewith an embodiment of the present disclosure;

FIG. 134 shows a plunger pump for use within a standard IV set tubingwith an actuator outside of the variable volume in accordance with anembodiment of the present disclosure;

FIG. 135 shows several views of a cam-driven linear peristaltic pumphaving pinch valves and a plunger inside a variable volume with acorresponding cam mechanism outside of the variable volume in accordancewith an embodiment of the present disclosure;

FIG. 136 shows a plunger pump having a plunger inside a variable volumewith an actuator outside of the variable volume in accordance with anembodiment of the present disclosure;

FIG. 137 shows a cam-driven linear peristaltic pump having a plungerinside a variable volume with a corresponding cam mechanism outside ofthe variable volume and pinch valves on the housing of the variablevolume in accordance with an embodiment of the present disclosure;

FIG. 138 shows a plunger pump having a plunger inside a variable volumeand pinch valves outside of the variable volume in accordance with anembodiment of the present disclosure;

FIG. 139 shows several views of a cam-driven linear peristaltic pumphaving a plunger inside a variable volume with a corresponding cammechanism and pinch valves outside of the variable volume in accordancewith an embodiment of the present disclosure;

FIG. 140 illustrates occlusion detection using a plunger pump having anAVS assembly and a spring-biased pinching mechanism inside the variablevolume in accordance with an embodiment of the present disclosure;

FIG. 141 shows a pump with a spring-loaded plunger within a variablevolume of an AVS assembly with an actuated plunger outside of thevariable volume in accordance with an embodiment of the presentdisclosure;

FIG. 142 shows a linear peristaltic pump with pinch valves and a camshaft disposed within a variable volume of an AVS assembly havingspring-biased pinching mechanism disposed therein, and a plunger and apinch valve outside of the variable volume in accordance with anembodiment of the present disclosure;

FIG. 143 shows a linear peristaltic pump with pinch valves and a plungerdisposed outside of a variable volume of an AVS assembly in accordancewith an embodiment of the present disclosure;

FIG. 144 shows a the stages of a plunger pump having a an optical sensoror camera to measure the volume within a tube residing within a chamberin accordance with an embodiment of the present disclosure;

FIG. 145 shows a plunger pump having a chamber having an optical sensorto estimate fluid volume of a tube having a spring-biased pinchmechanism around the tube and a plunger and pinch valves in accordancewith an embodiment of the present disclosure;

FIG. 146 shows a plunger pump having a chamber with an optical sensor toestimate fluid volume of a tube having a spring-biased pinch mechanismaround the tube and a plunger and pinch valves outside the chamber inaccordance with an embodiment of the present disclosure;

FIG. 147 shows several views of a plunger pump having an AVS assemblywith pinch valve disposed within the variable volume of the AVSassembly, and a plunger and pinch valve disposed outside the variablevolume in accordance with an embodiment of the present disclosure;

FIG. 148 shows an two cross-sectional views of the plunger pump of FIG.147 in accordance with an embodiment of the present disclosure;

FIG. 149 shows an alternative two cross-sectional views of the plungerpump of FIG. 147 in accordance with an embodiment of the presentdisclosure;

FIG. 150 illustrates the stages during normal operation of a plungerpump having a spring-biased plunger in accordance with an embodiment ofthe present disclosure;

FIG. 151 illustrates the stages for detecting an occlusion for a plungerpump having a spring-biased plunger in accordance with an embodiment ofthe present disclosure;

FIG. 152 illustrates the stages for leakage detection for a plunger pumphaving a spring-biased plunger in accordance with an embodiment of thepresent disclosure;

FIG. 153 illustrates the stages for detecting a failed valve and/orbubble dection for a plunger pump having a spring-biased plunger inaccordance with an embodiment of the present disclosure;

FIG. 154 illustrates the stages for empty reservoir detection and/orupstream occlusion detection for a plunger pump having a spring-biasedplunger in accordance with an embodiment of the present disclosure;

FIG. 155 illustrates the stages for free-flow prevention for a plungerpump having a spring-biased plunger in accordance with an embodiment ofthe present disclosure;

FIG. 156 illustrates the stages for a negative pressure valve check fora plunger pump having a spring-biased plunger in accordance with anembodiment of the present disclosure;

FIGS. 157-158 show views of a plunger pump having a cam shaft 671 thattraverses the variable volume of an AVS assembly in accordance with anembodiment of the present disclosure;

FIGS. 159-162 illustrate several cam profiles in accordance with severalembodiments of the present disclosure;

FIG. 163 illustrates a peristaltic pump having a plunger and a pinchvalves outside of an AVS chamber with two pinch valves on the interfaceof the ACS chamber in accordance with an embodiment of the presentdisclosure;

FIG. 164 illustrates several stages of operation of the peristaltic pumpof FIG. 163 in accordance with an embodiment of the present disclosure;

FIG. 165 illustrates a peristaltic pump having two plungers external toan AVS chamber in accordance with an embodiment of the presentdisclosure;

FIG. 166 illustrate several stages of the peristaltic pump of FIG. 165in accordance with an embodiment of the present disclosure;

FIG. 167 illustrates a peristaltic pump having a plunger with a linearsensor in accordance with an embodiment of the present disclosure;

FIG. 168 illustrates a graphic of data from the linear sensor of theperistaltic pump of FIG. 167 in accordance with an embodiment of thepresent disclosure;

FIG. 169 illustrates the stages of the peristaltic pump of FIG. 169 inaccordance with an embodiment of the present disclosure;

FIG. 170 illustrates the detection of an occlusion condition vis-à-vis anon-occluded condition in accordance with an embodiment of the presentdisclosure;

FIG. 171 illustrates the detection of a valve leak vis-à-vis afull-valve-sealing condition in accordance with an embodiment of thepresent disclosure;

FIG. 172 illustrates the detection of a too much air in the tube or avalve fail vis-à-vis a proper operation in accordance with an embodimentof the present disclosure;

FIG. 173 shows a block diagram that illustrates the electronics of aperistaltic pump in accordance with another embodiment of the presentdisclosure;

FIG. 174 shows a block diagram that illustrates the electronics of aperistaltic pump in accordance with another embodiment of the presentdisclosure;

FIG. 175 shows a perspective view of peristaltic pump in accordance withan embodiment of the present disclosure;

FIGS. 176-180 show data from several AVS sweeps in accordance with anembodiment of the present disclosure;

FIGS. 181, 182A-182C, and 183A-183C show several side views of a cammechanism of the peristaltic pump of FIG. 175 in accordance with anembodiment of the present disclosure;

FIG. 184 shows a sectional view of the pinch valves and plunger of theperistaltic pump of FIG. 175 in accordance with an embodiment of thepresent disclosure;

FIG. 185 show two views of a plunger with flexible fingers to grip atube in accordance with an embodiment of the present disclosure;

FIG. 186 shows an embodiment of a cam mechanism of a peristaltic pump inaccordance with an embodiment of the present disclosure;

FIG. 187 shows an embodiment of a cam mechanism of a peristaltic pump inaccordance with an embodiment of the present disclosure;

FIGS. 188-189 and 190A-190C show several views of a peristaltic pump inaccordance with the present disclosure;

FIGS. 191-195 show several views of a peristaltic pump in accordancewith an additional embodiment of the present disclosure;

FIGS. 196A-196B illustrate torque on a cam shaft of a peristaltic pumpin accordance with an embodiment of the present disclosure;

FIG. 197 illustrates a cam profile for several cams for a peristalticpump in accordance with an embodiment of the present disclosure;

FIG. 198 shows various feedback modes of a peristaltic pumps inaccordance with an embodiment of the present disclosure;

FIG. 199 shows a graph illustrating data of a linear sensor used toestimate fluid flow in accordance with an embodiment of the presentdisclosure;

FIGS. 200-206 show several perspective views of a peristaltic pumphaving a angular members interfacing into a cam in accordance with anembodiment of the present disclosure;

FIGS. 207-221 illustrate the operation of a slide occluder of theperistaltic pump of FIGS. 200-206 in accordance with an embodiment ofthe present disclosure;

FIG. 222-223 shows a two views of a peristaltic pump in accordance withan embodiment of the present disclosure;

FIGS. 224-238 shows several views of the peristaltic pump of FIGS.222-223 illustrating the operation of the slide occluder in accordancewith an embodiment of the present disclosure;

FIGS. 239-245 show several view of the peristaltic pump of FIGS. 222-238in accordance with an embodiment of the present disclosure;

FIGS. 246-250 show several views of an integrated cam and motor in foruse in an peristaltic pump disclosed herein in accordance with anotherembodiment of the present disclosure;

FIGS. 251-254 illustrate a camera sensor for use for measuring theposition of a plunger and pinch valves of a peristaltic pump inaccordance with an embodiment of the present disclosure;

FIG. 255 illustrates a peristaltic pump having L-shaped cam followers inan exploded view of the mechanical elements from the top of the pump;

FIGS. 256A-256B illustrate the peristaltic pump having L-shaped camfollowers in an exploded view of the mechanical elements from the bottomof the pump;

FIG. 257 illustrates the peristaltic pump having L-shaped cam followerswith a door open in an isometric view of the mechanical elements fromthe top of the pump;

FIG. 258 illustrates the peristaltic pump having L-shaped cam followersin an exploded view showing the PCB, pump body, door, and a motor with agear head;

FIG. 259 illustrates the slide occluder inserted into the open door ofthe peristaltic pump having L-shaped cam followers;

FIG. 260 illustrates the peristaltic pump having L-shaped cam followerswith the door open and some elements removed to reveal the cam-shaft,pump and valves;

FIG. 261 illustrates the insertion of the slide occluder into the opendoor of the peristaltic pump having L-shaped cam followers;

FIGS. 262-263 shows an alternative door with the door half of analternative split carriage;

FIG. 264 illustrates the door, a lever and a slide carriage of theperistaltic pump having L-shaped cam followers in an exploded view;

FIG. 265 illustrates the peristaltic pump having L-shaped cam followerswith the door open in an isometric view of the mechanical elements fromthe bottom of the pump;

FIG. 266 illustrates a cam-shaft of the peristaltic pump having L-shapedcam followers in an isometric view;

FIG. 267 illustrates the plunger cam follower of the peristaltic pumphaving L-shaped cam followers in an isometric view from the front;

FIG. 268 illustrates the plunger cam follower of the peristaltic pumphaving L-shaped cam followers in an isometric view from the back;

FIG. 269 illustrates the valve cam follower of the peristaltic pumphaving L-shaped cam followers in an isometric view from a first side;

FIG. 270 illustrates the valve cam follower of the peristaltic pumphaving L-shaped cam followers in an isometric view from a second side;

FIG. 271 illustrates a outlet cam of the peristaltic pump havingL-shaped cam followers in an orthographic view;

FIG. 272 illustrates a pump cam of the peristaltic pump having L-shapedcam followers in an orthographic view;

FIG. 273 illustrates a intake cam of the peristaltic pump havingL-shaped cam followers in an orthographic view;

FIG. 274 illustrates the plunger and valve cam followers of theperistaltic pump having L-shaped cam followers in an exploded view;

FIG. 275 illustrates retainers for the springs on the cam followers ofthe peristaltic pump having L-shaped cam followers in an isometric view;

FIG. 276 shows a cross-section of the pump including sections of thecam, plunger and platen;

FIG. 277 shows a cross-sectional view of the plunger compressing theinfusion tube against the platen;

FIG. 278 illustrates the housing, cam shaft and cam followers of theperistaltic pump having L-shaped cam followers in an exploded view;

FIG. 279 illustrates the upper and lower housing of the peristaltic pumphaving L-shaped cam followers in an isometric view;

FIG. 280 illustrates the assembled upper and lower housing of theperistaltic pump having L-shaped cam followers in isometric views

FIG. 281 illustrates the assembled upper and lower housing of theperistaltic pump having L-shaped cam followers in isometric views

FIG. 282 illustrates the peristaltic pump having L-shaped cam followerswith PCB removed to reveal magnets on the plunger and correspondingsensors on PCB;

FIG. 283 illustrates the insertion of the slide occluder into the opendoor of the peristaltic pump having L-shaped cam followers;

FIG. 284 illustrates the slide occluder inserted into the open door ofthe peristaltic pump having L-shaped cam followers;

FIG. 285 illustrates the split-carriage in the open position;

FIG. 286 illustrates the split-carriage in the closed position;

FIG. 287 illustrates the peristaltic pump having L-shaped cam followerswith the door partially closed and some elements removed to reveal theslide occluder in the closed split-carriage;

FIG. 288 illustrates the multi-part link between the split carriage andthe lever in an isometric view;

FIG. 289 illustrates the peristaltic pump having L-shaped cam followerswith the door closed and some elements removed to reveal the slideoccluder in the closed split-carriage;

FIGS. 290-293 illustrate four steps of closing the door of theperistaltic pump having L-shaped cam followers;

FIG. 294 illustrates a lever on the door engaging a pin on the body ofthe peristaltic pump having L-shaped cam followers;

FIG. 295 illustrates a spring element in the door of the peristalticpump having L-shaped cam followers;

FIG. 296 illustrates two latch hooks of the lever on the door of theperistaltic pump having L-shaped cam followers;

FIG. 297 shows a vertical cross-sectional view of the peristaltic pumpwith L-shaped cam followers;

FIG. 298 shows a horizontal cross-sectional view of the peristaltic pumpwith L-shaped cam followers;

FIG. 299 illustrates a spring-pin engaging a detent on the lever latchhook in the closed position within the door of the peristaltic pumphaving L-shaped cam followers;

FIG. 300 illustrates a spring-pin engaging a detent on the lever latchhook in the open position within the door of the peristaltic pump havingL-shaped cam followers;

FIG. 301 illustrates a slide-occluder detection lever displaced by theslide occluder when the door is on the peristaltic pump having L-shapedcam followers;

FIG. 302 illustrates a latch hook detection lever displaced by the latchhook when the door is on the peristaltic pump having L-shaped camfollowers;

FIGS. 303-306 show several views of a patient bedside system inaccordance with an embodiment of the present disclosure;

FIG. 307 shows a close-up view of a portion of an interface of a clampthat is attachable to a pump shown in FIGS. 303-306 in accordance withan embodiment of the present disclosure;

FIG. 308 shows another close-up view of another portion of the interfaceshown in FIG. 301 in accordance with an embodiment of the presentdisclosure;

FIG. 309 shows a perspective view of a pump shown in FIGS. 303-306 inaccordance with an embodiment of the present disclosure;

FIG. 310 shows a perspective view of a pump shown in FIGS. 303-306 inaccordance with an embodiment of the present disclosure;

FIG. 311 shows a perspective view of a pump with the graphic userinterface shown on the screen in accordance with an embodiment of thepresent disclosure;

FIG. 312 shows an example infusion programming screen of the graphicuser interface in accordance with an embodiment of the presentdisclosure;

FIG. 313 shows an example infusion programming screen of the graphicuser interface in accordance with an embodiment of the presentdisclosure;

FIG. 314 shows an example infusion programming screen of the graphicuser interface in accordance with an embodiment of the presentdisclosure;

FIG. 315 shows an example infusion programming screen of the graphicuser interface in accordance with an embodiment of the presentdisclosure;

FIG. 316 shows an example infusion programming screen of the graphicuser interface in accordance with an embodiment of the presentdisclosure;

FIG. 317 shows an infusion rate over time graphical representation of anexample infusion in accordance with an embodiment of the presentdisclosure;

FIG. 318 shows an infusion rate over time graphical representation of anexample infusion in accordance with an embodiment of the presentdisclosure;

FIG. 319 shows an infusion rate over time graphical representation of anexample infusion in accordance with an embodiment of the presentdisclosure;

FIG. 320 shows an infusion rate over time graphical representation of anexample infusion in accordance with an embodiment of the presentdisclosure;

FIG. 321 shows an infusion rate over time graphical representation of anexample infusion in accordance with an embodiment of the presentdisclosure;

FIG. 322 shows an example drug administration library screen of thegraphic user interface in accordance with an embodiment of the presentdisclosure;

FIG. 323 shows a schematic of a battery powered draw speaker;

FIG. 324 illustrates an electrical block diagram of peristaltic pump inaccordance with an embodiment of the present disclosure;

FIG. 325 illustrates the electrical block diagram of FIG. 324 withdivisions for use with reference to FIGS. 325A-325G in accordance withan embodiment of the present disclosure;

FIG. 325A-325G illustrates a detailed electrical block diagram ofperistaltic pump in accordance with an embodiment of the presentdisclosure;

FIG. 326 presents a linear encoder signal over cam angle graph inaccordance with an embodiment of the present disclosure;

FIG. 327 illustrates a volume over time graph in accordance with anembodiment of the present disclosure;

FIG. 328 illustrates a cam shaft angle over volume graph in accordancewith an embodiment of the present disclosure;

FIG. 329 illustrates a possible measured pressure vs. time trace of adelivery line downstream of peristaltic pump in accordance with anembodiment of the present disclosure;

FIG. 330 is a state diagram in accordance with an embodiment of thepresent disclosure;

FIG. 331 is a software block diagram in accordance with an embodiment ofthe present disclosure;

FIG. 332 is a software block diagram in accordance with an embodiment ofthe present disclosure;

FIG. 333 shows a feedback based control loop to control a motor of aninfusion pump in accordance with an embodiment of the presentdisclosure;

FIG. 334 shows a process diagram to illustrate the software operation ofan infusion pump in accordance with an embodiment of the presentdisclosure; and

FIGS. 335-336 shows two dual-band antennas for use with an infusion pumpin accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 shows a block diagram of a system 1 for infusing fluid. System 1includes fluid reservoirs 2, 3, and 4 for infusing the fluid containedtherein into a patient 5. The fluid reservoirs 2, 3, and 4 are gravityfed into drip chambers 7, 8, and 9, respectively. The drip chambers 7,8, and 8 are respectively fed into flow meters 10, 11, and 12. From theflow meters 10, 11, and 12, the fluid is fed into free-flow detectors13, 14, and 15, respectively.

System 1 also includes valves 16, 17, and 18 from a respective free-flowdetector of the free-flow detectors 13, 14, and 15. Pumps 19, 20, and 21receive fluid from valves 16, 17, and 18, and combine the fluid using aconnector 22. The valves 16, 17, and 18 may be in wireless or wiredcommunication with a respective pump 19, 20, and 21 to control the flowrate and/or discharge profile. For example, the pump 19 may communicatewirelessly with the valve 16 to adjust the opening and closing of thevalve 16 to achieve a target flow rate, for example, when the pump 19runs at a predetermined speed; the valves 16 may be downstream from thepump 19 in some embodiments.

Fluid from the connector 22 is fed into an occlusion detector 23 whichis fed into an air detector 24. The occlusion detector 23 can detectwhen an occlusion exists within tubing of the system 1. The occlusiondetector 23 may be a pressure sensor compressed against the tube suchthat increases beyond a predetermined threshold is indicative of anocclusion. The air detector 24 detects if air is present in the tubing,e.g., when flowing towards the patient 5. Prior to entering into aninfusion site monitor 26, the fluid passes through a valve 25.

The monitoring client 6, in some embodiments, monitors operation of thesystem 1. For example, when an occlusion is detected by occlusiondetector 23 and/or air is detected by the air detector 24, themonitoring client 6 may wirelessly communicate a signal to the valve 25to shut-off fluid flow to the patient 5.

The monitoring client 6 may also remotely send a prescription to apharmacy. The prescription may be a prescription for infusing a fluidusing a fluid pump. The pharmacy may include one or more computersconnected to a network (e.g., the internet) to receive the prescriptionand queue the prescription within the one or more computers. Thepharmacy may use the prescription to compound the drug (e.g., using anautomated compounding device coupled to the one or more computers ormanually by a pharmacist viewing the queue of the one or morecomputers), pre-fill a fluid reservoir associated with an infusion pump,and/or program the infusion pump (e.g., a treatment regime is programmedinto the infusion pump 19) at the pharmacy in accordance with theprescription. The fluid reservoir 2 may be automatically filled by theautomated compounding device and/or the infusion pump 19 may beautomatically programmed by the automated compounding device. Theautomated compounding device may generate a barcode, RFID tag 29 and/ordata. The information within the barcode, RFID tag 29, and/or data mayinclude the treatment regime, prescription, and/or patient information.The automated compounding device may: attach the barcode to the fluidreservoir 2 and/or the infusion pump 19; attach the RFID tag 29 to thefluid reservoir 2 and/or the infusion pump 19; and/or program the RFIDtag 29 or memory within the fluid reservoir 2 or the infusion pump 19with the information or data. The data or information may be sent to adatabase (e.g., electronic medical records) that associates theprescription with the fluid reservoir 2 and/or the infusion pump 19,e.g., using a serial number or other identifying information within thebarcode, RFID tag 29, or memory.

The infusion pump 19 may have a scanner, e.g., an RFID interrogator thatinterrogates the RFID tag 29 or a barcode scanner that scans a barcodeof the fluid reservoir 2, to determine that it is the correct fluidwithin the fluid reservoir 2, it is the correct fluid reservoir 2, thetreatment programmed into the infusion pump 19 corresponds to the fluidwithin the fluid reservoir 2 and/or the fluid reservoir 2 and infusionpump 19 are correct for the particular patient (e.g., as determined froma patient's barcode, RFID 27, or other patient identification). Forexample, the infusion pump 19 may scan the RFID tag 29 of the fluidreservoir 2 and check if the serial number or fluid type encoded withinthe RFID tag 29 is the same as indicated by the programmed treatmentwithin the infusion pump 19. Additionally or alternatively, the infusionpump 19 may interrogate the RFID tag 29 of the fluid reservoir 2 for aserial number and the RFID tag 27 of the patient 5 for a patient serialnumber, and also interrogate the electronic medical records to determineif the serial number of the fluid reservoir 19 within the RFID tag 29matches a patient's serial number within the RFID tag 27 as indicated bythe electronic medical records. Additionally or alternatively, themonitoring client 6 may scan the RFID tag 29 of the fluid reservoir 2and an RFID tag of the infusion pump 19 to determine that it is thecorrect fluid within the fluid reservoir 2, it is the correct fluidreservoir 2, the treatment programmed into the infusion pump 19corresponds to the fluid within the fluid reservoir 2, and/or the fluidreservoir 2 and infusion pump 19 are correct for the particular patient(e.g., as determined from a patient's barcode, RFID tag 27, electronicmedical records, or other patient identification or information).Additionally or alternatively, the monitoring client 6 or the infusionpump 19 may interrogate an electronic medical records database and/orthe pharmacy to verify the prescription or download the prescription,e.g., using a barcode serial number on the infusion pump 19 or fluidreservoir 2.

Additionally or alternatively, the flow from the pumps 19, 20, and 21may be monitored and/or controlled by the monitoring client 6 to ensuresafe drug delivery. The monitoring client 6 may scan a RFID tag 27 on abracelet 28, and also RFID tags 29, 30, and 31 on the fluid reservoirs,2, 3, and 4, respectively. The monitoring client 6 may downloadelectronic medical records (“EMR”) associated with the RFID tag 27 onthe patient's 5 bracelet, and compare it to one or more prescriptionsfound in the EMR of the patient 5. If the EMR indicates that the fluidreservoirs 2, 3, and 4 contain the correct medication, a user can inputinto the monitoring client 6 a command to start pumping fluid throughpumps 19, 20, and/or 21 into the patient 5.

The infusion site monitor 26 monitors the site at which the fluid is fedinto the patient 5. The infusion site monitor 26 receives the fluidthrough an input port 408 and feeds the fluid to the patient 5 throughan output port 409. As shown in FIG. 2, in some embodiments the infusionsite monitor 5 optionally includes an air detector 410, an infiltrationdetector 32, a pressure sensor 33, a fluid-temperature sensor 34, and/ora patient temperature sensor 35. In some embodiments, the infusion sitemonitor 26 optionally includes an ambient air temperature sensor 35 andan RFID interrogator 41A.

The infusion site monitor 26 also includes a processor 37 and a memory38. The memory 38 may include processor executable instructionsconfigured for execution on the processor 37. The processor 37 is inoperative communication with the air detector 410, the infiltrationdetector 32, the pressure sensor 33, the fluid-temperature sensor, thepatient temperature sensor 35, the ambient air temperature sensor 36,the RFID interrogator 41A, the user input 39, and the buttons 40; forexample, the processor 37 may be coupled to a bus, a parallelcommunication link, a serial communication link, a wirelesscommunication link, and the like. Referring to FIGS. 1 and 2,information from the various circuitry of 410, 32, 33, 34, 35, 36, 39,40, and/or 41 may be communicated to the monitoring client 6 via a wiredor wireless communication link, e.g., WiFi, USB, serial, WiMax,Bluetooth, Zigbee, and the like.

In FIG. 1, in each of the pumps 19, 20, and 21, or the fluid reservoirs2, 3, and 4 may include an upstream and/or downstream pressuregenerating source (e.g., an occluder, speaker, etc) to generate apressure “signature” that would travel along the line and into the otherdevices, e.g., pumping, monitoring, or metering devices. These pressuresignatures may indicate the pressure in each of the lines, may be usedto identify each line and coordinate the flow rates of the lines, and/ormay indicate what the measured flow rate of the line should be. Thepressure signature may be an ultrasonic signal generated by apiezoelectric ceramic that is modulated to encode information such asdigital data or an analog signal, e.g., an acoustic carrier frequencywith FM modulation, AM modulation, digital modulation, analogmodulation, or the like.

For example, each of the pumps 19, 20, and 21 may transmit soundpressure down the IV line to the infusion site monitor 26 (which mayinclude a transducer to detect these pressure waves) indicating to theinfusion site monitor 26 the expected total flow rate therethrough. Aflow rate meter 169 (see FIG. 2) may measure the liquid flow rate, andif the measured liquid flow rate deviates by a predetermined amount, theinfusion site monitor 26 may issue an alarm and/or alert, e.g., thealarm may signal the valves 16, 17, 18, and 25 to close, and/or themonitoring client 6 may use the information for logging purposes and/orto cause the valves 16, 17, 18, and 25 to close.

Referring again to FIG. 2 and as previously mentioned, the processor 37is in operative communication with user input 39 and one or more buttons40. The infusion site monitor 26 may receive various user input 39 tosignal the processor 37 to start monitoring treatment of the patient 5.Additionally or alternatively, the infusion site monitor 26 mayinterrogate the RFID 27 of the patient's 5 bracelet (see FIG. 1) todetermine if the infusion site monitor 26 is coupled to the correctpatient 5.

The air detector 410 is in operative communication with the processor37. The air detector 410 can measure, estimate, and/or determine theamount of air entering into the infusion site monitor 26 via the inputport 29. In some embodiments, when the processor 37 determines that airwithin the tube exceeds a predetermined threshold, the processor 37communicates an alarm or alert to the monitoring client 6 (see FIG. 1)which can signal valve 25 to shut off fluid flow to the patient 5.Additionally or alternatively, the processor 37 may communicate an alarmor an alert to the valve 25 or to one or more of the pumps 19, 20, and21 to stop fluid flow when the air within the tube exceeds thepredetermined threshold. The air detector 410 may be an ultrasonic airdetector, an impedance-based air detector, and the like.

The infiltration detector 32 is in operative communication with theprocessor 37. The infiltration detector 32 can measure, estimate, and/ordetermine the amount of blood entering into the infusion site monitor 26via the output port 30 during an infiltration test. In some embodiments,when the processor 37 determines that blood within the tube is less thana predetermined threshold during an infiltration test, the processor 37communicates an alarm or alert to the monitoring client 6 (see FIG. 1)which can signal the valve 25 to shut off fluid flow to the patient 5.Additionally or alternatively, the processor 37 may communicate an alarmor an alert to the valve 25 or to one or more of the pumps 19, 20, and21 to stop fluid flow when the infiltration tests determines that aninfiltration has occurred. The infiltration test may include reversingone or more of the pumps 19, 20, and/or 21 to determine if blood doesflow into the infusion site monitor 26. When an infiltration hasoccurred, blood will not easily flow into the infusion site monitor 26.Thus, when fluid is pulled from the patient 5, blood should enter intothe tube 41 with a predetermined minimum amount of backward pumping whenno infiltration has occurred. The infiltration detector 32 may be CCDbased, camera based, optical based, and the like.

The pressure sensor 33 is in operative communication with the processor37. The pressure sensor 33 can measure, estimate, and/or determine theamount of pressure entering, exiting and/or flowing through the infusionsite monitor 26 via the ports 29 and 30. In some embodiments, when theprocessor 37 determines that pressure in the tube exceeds apredetermined threshold and/or is below a predetermined threshold, theprocessor 37 communicates an alarm or alert to the monitoring client 6(see FIG. 1) which can signal valve 25 to shut off fluid flow to thepatient 5. The pressure sensor 33 may be a resistive element thatchanges in resistance as a force is applied to the resistive element,the resistive element is stretched, and/or the resistive element ispulled. The resistive element may be wrapped around the tube 41 suchthat as the pressure of the fluid causes the tube 41 to expand, theresistance of the resistive element is measured and is associated with apressure within the tube, e.g., the resistance may be measured and alook-up table may be used to look up an estimated pressure within thetube 41. In some embodiments, when the processor 37 determines thatpressure within the tube is greater than a predetermined maximum valueor less than predetermined minimum value, the processor 37 communicatesan alarm or alert to the monitoring client 6 (see FIG. 1) which cansignal the valve 25 to shut off fluid flow to the patient 5.Additionally or alternatively, the processor 37 may communicate an alarmor an alert to the valve 25 or to one or more of the pumps 19, 20, and21 to stop fluid flow when the processor 37 receives from the pressuresensor 33 to a measured pressure within the fluid line 41 greater than apredetermined maximum value or less than predetermined minimum value.

The fluid-temperature sensor 34 is in operative communication with theprocessor 37. The fluid-temperature sensor 34 can measure, estimate,and/or determine the temperature of the fluid within the tube 41. Insome embodiments, when the processor 37 determines that temperature ofthe fluid within the tube 41 exceeds a predetermined threshold and/or isbelow a predetermined threshold, the processor 37 communicates an alarmor alert to the monitoring client 6 (see FIG. 1) which can signal valve25 to shut off fluid flow to the patient 5. In some embodiments, a usermay override the alarm or alert, e.g., using a touch screen of themonitoring client 6. Additionally or alternatively, the processor 37 maycommunicate an alarm or an alert to the valve 25 or to one or more ofthe pumps 19, 20, and 21 to stop fluid flow when the processor 37receives a estimated temperature of the fluid within the tube 41indicating the fluid is above a predetermined threshold and/or is belowa predetermined threshold. The fluid-temperature sensor 34 may utilize atemperature sensitive material, a positive temperature-coefficientmaterial, a negative temperature-coefficient material, or othertemperature sensor technology.

The patient temperature sensor 35 is in operative communication with theprocessor 37. The patient temperature sensor 35 can measure, estimate,and/or determine the temperature of the patient 5 (see FIG. 1). Thetemperature of the patient 5 may be used to determine the condition ofthe patient, compliance with a temperature affecting medication, oreffect of a temperature affecting medication. The temperature of thepatient 5 (a patient-condition parameter) may be communicated to themonitoring client 6 (see FIG. 1). In some embodiments, when theprocessor 37 determines that the temperature of the patient 3 exceeds apredetermined threshold or is below a predetermined threshold, theprocessor 37 communicates an alarm or alert to the monitoring client 6(see FIG. 1) which can signal valve 25 to shut off fluid flow to thepatient 5, send an alert to a remote communicator, and/or notify acaregiver of the condition via an internal speaker 42 or vibration motor43 within the infusion site monitor 26. Additionally or alternatively,the processor 37 may communicate an alarm or an alert to the valve 25 orto one or more of the pumps 19, 20, and 21 to stop fluid flow when theprocessor 37 receives an estimated temperature from the patienttemperature sensor 35 that exceeds a predetermined threshold or is belowa predetermined threshold. The patient temperature sensor 35 may utilizea temperature sensitive material, a positive temperature-coefficientmaterial, a negative temperature-coefficient material, or othertemperature sensor technology.

The ambient air temperature sensor 36 is in operative communication withthe processor 37. The ambient air temperature sensor 36 can measure,estimate, and/or determine the temperature of the ambient air within theinfusion site monitor 26, or in other embodiments, the temperate of theair outside of the infusion site monitor 26. An excessive ambient airtemperature may be an indication of an electronic component failure, insome specific embodiments. In some embodiments, when the processor 37determines that the temperature from the ambient air temperature sensor36 exceeds a predetermined threshold or is below a predeterminedthreshold, the processor 37 communicates an alarm or alert to themonitoring client 6 (see FIG. 1) which can signal valve 25 to shut offfluid flow to the patient 5. Additionally or alternatively, theprocessor 37 may communicate an alarm or an alert to the valve 25 or toone or more of the pumps 19, 20, and 21 to stop fluid flow when theprocessor 37 receives an estimated temperature from the ambienttemperature sensor 36 that exceeds a predetermined threshold or is belowa predetermined threshold. The ambient air temperature sensor 36 mayutilize a temperature sensitive material, a positivetemperature-coefficient material, a negative temperature-coefficientmaterial, or other temperature sensor technology.

Referring to the drawings, FIG. 3 shows a block diagram of a pump forinfusing liquid of the system of FIG. 1 in accordance with an embodimentof the present disclosure. Although the pump 19 of FIG. 3 is describedas being pump 19 of FIG. 1, the pump 19 of FIG. 3 may be one or more ofthe pumps 19, 20, and 21 of FIG. 1, or may be included within anysufficient pump disclosed herein.

Pump 19 includes a processor 37 coupled to a memory 38. The processor 37is in operative communication with the memory 38 to receive processorexecutable instructions configured for execution on the processor 37. Insome embodiments, the processor 37 is, optionally, in operativecommunication with the user input 39, the air detector 410, the fluidtemperature sensor 34, valves 47, 49, 51 and 52, a flow meter 48, anactuator 54, an air filter 50, a drain chamber 53, and/or a pressuresensor 33.

The pump includes an actuator 54 which operates on fluid containedwithin tubing 56 flowing through the pump. The actuator 54 may directlyoperate on the tube 56, or may actuate against one or more membranescontained within the actuator 54. In some embodiments, the valves 47 and49 cooperate with the actuator 54 to pump fluid, e.g., liquid, from theinput port 44 to the output port 45 through the tube 56. In someembodiments of the present disclosure, the pump 19 contains no internaltubing and interfaces to external tubing.

The air filter 50 filters out air from the tube 56. In alternativeembodiments, the air filter 50 is upstream from the air detector 410.Valve 52 can activate to allow air to enter in from the tube 56 into adrain chamber 53 via a diversion tube 57.

Referring to the drawings, FIGS. 4 and 5 show a drip-chamber holder 58receiving a drip chamber 59. As described infra, the drip-chamber holder58 includes a free-flow detector in accordance with an embodiment of thepresent disclosure. Additionally, alternatively, or optionally, thedrip-chamber holder 58 may include a flow-rate meter in accordance withsome embodiments of the present disclosure. FIG. 4 shows the dripchamber holder 58 with a shut door 62, and FIG. 5 shows the drip-chamberholder 58 with an open door 62. The drip chamber holder 58 may includethe drip chamber 7, the flow meter 10, and the freeflow detector 13 ofFIG. 1 integrated together, or some combination thereof. The dripchamber holder 58 includes a start button 60 and a stop button 61. Thedrip-chamber holder may include a valve to stop fluid from flowingtherethrough or may signal another valve, e.g., valve 16 of FIG. 1, tostop the fluid from flowing.

The drip-chamber holder 58 optionally includes cameras 63 and 64 thatcan estimate fluid flow and/or detect free flow conditions. Although thedrip-chamber holder 58 includes two cameras (e.g., 63 and 64), only oneof the cameras 64 and 64 may be used in some embodiments. The cameras 63and 64 can image a drop while being formed within the drip chamber 59and estimate its size. The size of the drop may be used to estimatefluid flow through the drip chamber 59. For example, in some embodimentsof the present disclosure, the cameras 63 and 64 use an edge detectionalgorithm to estimate the outline of the size of a drop formed withinthe drip chamber 59; a processor therein (see processor 90 of FIGS. 12of 14, for example) may assume the outline is uniform from every angleof the drop and can estimate the drop's size from the outline. In theexemplary embodiment shown in FIGS. 4 and 5, the two cameras 63 and 64may average together the two outlines to estimate the drop's size. Thecameras 63 and 64 may use a reference background pattern to facilitatethe recognition of the size of the drop as described herein.

In another embodiment of the present disclosure, the cameras 63 and 64image the fluid to determine if a free flow condition exists. Thecameras 63 and 64 may use a background pattern to determine if the fluidis freely flowing (i.e., drops are not forming and the fluid streamsthrough the drip chamber 59). Although the drip-chamber holder 58includes two cameras (e.g., 63 and 64), only one of the cameras 64 and64 may be used in some embodiments to determine if a free flow conditionexists

Additionally or alternatively, in some embodiments of the presentdisclosure, another camera 65 monitors the fluid line 66 to detect thepresence of one or more bubbles within the fluid line. In alternativeembodiments, other bubble detectors may be used in place of the camera65. In yet additional embodiments, no bubble detection is used in thedrip-chamber holder 58.

FIG. 6 shows a block diagram of another drip-chamber holder 67 inaccordance with another embodiment of the present disclosure. Thedrip-chamber holder 67 includes an optical drip counter 68 that receivesfluid from an IV bag 69. In alternative embodiments, the optical dripcounter 68 is a camera, is a pair of cameras, is a capacitive dripcounter, and the like. The drip-chamber holder 67 is coupled to a tube70 coupled to a holder clamp 71 that is controlled by a motor 72. Themotor 72 may be coupled to a lead screw mechanism 73 to control a rollerclamp 74.

The motor 72 may be a servo-motor and may be used to adjust the flowrate through the tube 70. That is, the drip-chamber holder 67 may alsofunction as a flow meter and regulator. For example, a processor 75within the drip-chamber holder 67 may adjust the motor 72 such that adesired flow rate is achieved as measured by the optical drip counter68. The processor 75 may implement a control algorithm using the opticaldrip counter 68 as feedback, e.g., a proportional-integral-derivative(“PID”) control loop with the output being to the motor 72 and thefeedback being received from the optical drip counter 68.

In alternative embodiments, the motor 72, the lead screw mechanism 73,and the roller clamp 74 may be replaced and/or supplemented by anactuator that squeezes the tube 70 (e.g., using a cam mechanism orlinkage driven by a motor) or may be replaced by any sufficient roller,screw, or slider driven by a motor.

The drip-chamber holder 67 may also include a display, e.g., the display76 as shown on the drip-chamber holder 58 of FIGS. 4 and 5. The displaymay be used to set the target flow rate, display the current flow rate,and/or may provide a button, e.g., a touch screen button, to stop theflow rate (or a button 61 as shown in FIGS. 4 and 5 may be used to stopfluid flow).

Referring again to FIG. 4, in some specific embodiments of the presentdisclosure, the cameras 63 and/or 64 may be a camera cube manufacturedby OmniVision of 4275 Burton Drive, Santa Clara, Calif. 95054; forexample, the camera cube may be one manufactured for phone cameraapplications. In some embodiments of the present disclosure, the cameras63 and/or 64 may use a fixed focus and have a depth of field (“DOF”)from 15 centimeters to infinity.

The cameras 63 and 64 may each have the blur circle of a point imaged inthe range of one of the cameras 63 and/or 64 entirely contained withinthe area of a single pixel. In an exemplary embodiment, the focal lengthof the camera lenses of cameras 63 and 64 may be 1.15 millimeters, theF# may be 3.0, and the aperture of the lenses of cameras 63 and 64 maybe 0.3833 millimeter. A first order approximation to the optical systemof one or more of the cameras 63 and 64 may be made using matrixequations, where every ray, r, is represented as the vector described inEquation (1) as follows:

$\begin{matrix}{r = {\left\{ \frac{h}{\theta} \right\}.}} & (1)\end{matrix}$

In Equation (1) above, h is the height of the ray at the entrance to thecamera system of cameras 63 and/or 64, and θ is the angle of the ray.Referring to FIG. 7, when imaging a hypothetical point at a distanced_(im) from the lens of one of the cameras 63 or 64 (which has focallength f) and the lens is a distance d_(fp) from the focal plane, thecorresponding matrix, M_(cam), describing the camera (e.g., one or bothof the cameras 63 and/or 64) is described by Equation (2) as follows:

$\begin{matrix}{M_{cam} = {\begin{bmatrix}1 & d_{fp} \\0 & 1\end{bmatrix} \cdot \begin{bmatrix}1 & 0 \\{- \frac{1}{f}} & 1\end{bmatrix} \cdot {\begin{bmatrix}1 & d_{im} \\0 & 1\end{bmatrix}.}}} & (2)\end{matrix}$

To find the place on the focal plane, fp, where the ray strikes, amatrix multiplication as described in Equation (3) as follows may beused:

$\begin{matrix}{\left\{ \frac{h_{fp}}{\theta_{fp}} \right\} = {M_{cam} \cdot {\left\{ \frac{h_{im}}{\theta_{im}} \right\}.}}} & (3)\end{matrix}$

As illustrated in FIG. 7, the diameter of the blur circle, D_(blur), isshown as approximately the distance between the two points illustratedin FIG. 7. This distance is found by tracing rays from the point d_(im)away from the lens on the optical axis to the edges of the lens and thento the focal plane. These rays are given by the vectors shown in (4) asfollows:

$\begin{matrix}{\begin{Bmatrix}0 \\\left( {{\pm \tan^{- 1}}\frac{D_{lens}}{2*d_{im}}} \right)\end{Bmatrix}.} & (4)\end{matrix}$

As shown in FIG. 8, the blur circle, D_(blur), is calculated and shownfor a variety of lens-to-focal plane separations and lens-to-imageseparations. A contour map 77 is also shown in FIG. 8. The x-axis showsthe distance in microns between the focal plane and a point located afocal length away from the lens of one of the cameras 63 and/or 64. They-axis shows the distance in meters between the lens and the point beingimaged. The values creating the contour map 77 is the blur size dividedby the pixel size; therefore anything about 1 or less is sufficient forimaging. As shown in FIG. 8, the focal plane is located a focal lengthand an additional 5 micrometers away from the lens.

The cameras 63 and/or 64 may utilize a second lens. For example, one ormore of the cameras 63 and/or 64 may utilize a second lens to create arelatively larger depth of field and a relatively larger field of view.The depth of field utilizing two lenses can be calculated using the sameanalysis as above, but with the optical matrix modified to accommodatefor the second lens and the additional distances, which is shown inEquation (5) as follows:

                                       (5) $M_{sys} = {\begin{bmatrix}1 & d_{fp} \\0 & 1\end{bmatrix} \cdot \begin{bmatrix}1 & 0 \\{- \frac{1}{f_{cam}}} & 1\end{bmatrix} \cdot \begin{bmatrix}1 & d_{lens} \\0 & 1\end{bmatrix} \cdot \begin{bmatrix}1 & 0 \\{- \frac{1}{f_{lens}}} & 1\end{bmatrix} \cdot {\begin{bmatrix}1 & d_{im} \\0 & 1\end{bmatrix}.}}$

FIGS. 9 and 10 illustrate the field changes with the separation betweenthe lens and the camera and the corresponding change in the focus of thecamera. FIGS. 9 and 10 show the blur circle divided by the pixel size.FIG. 9 shows the blur circle divided by pixel size when a 20 millimeterfocal length lens is used. FIG. 10 shows the blur circle divided bypixel size when a 40 millimeter focal length lens is used. Thecorresponding fields of views about the optical axis for the corners ofthe two configurations of FIGS. 9 and 10 are shown in the table in FIG.11.

As shown in FIG. 11, in some embodiments, the cameras 63 and 64 of FIGS.4 and 5 may utilize a 40 mm to 60 mm focal length lens; thisconfiguration may include placing one or more of the cameras 43 and 64about 2 inches from the focus. In other embodiments of the presentdisclosure, other configurations may be used including those not shownin FIG. 11.

For example, the following analysis shows how the depth of field can beset for one or more of the cameras 63 and 65: using a lens of focallength, f, a distance, z, from the focal plane, and a distance, d, froma point in space; a matrix of the system is shown in Equation (6) asfollows:

$\begin{matrix}{M = {\begin{bmatrix}1 & z \\0 & 1\end{bmatrix} \cdot \begin{bmatrix}1 & 0 \\{- \frac{1}{f}} & 1\end{bmatrix} \cdot {\begin{bmatrix}1 & d \\0 & 1\end{bmatrix}.}}} & (6)\end{matrix}$

Equation (6) reduces to Equation (7) as follows:

$\begin{matrix}{M = {\begin{bmatrix}1 & z \\0 & 1\end{bmatrix} \cdot {\begin{bmatrix}1 & d \\{- \frac{1}{f}} & {1 - \frac{d}{f}}\end{bmatrix}.}}} & (7)\end{matrix}$

Equation (7) reduces to Equation (8) as follows:

$\begin{matrix}{M = {\begin{bmatrix}{1 - \frac{z}{f}} & {d + z - \frac{dz}{f}} \\{- \frac{1}{f}} & {1 - \frac{d}{f}}\end{bmatrix}.}} & (8)\end{matrix}$

Considering the on-axis points, all of the heights will be zero. Thepoint on the focal plane where different rays will strike is given by(9) as follows:

$\begin{matrix}{\left( {d + z - \frac{dz}{f}} \right){\theta.}} & (9)\end{matrix}$

As shown above in (9), 0 is the angle of the ray. The point in perfectfocus is given by the lens maker's equation given in Equation (10) asfollows:

$\begin{matrix}{\frac{1}{f} = {\frac{1}{z} + {\frac{1}{d}.}}} & (10)\end{matrix}$

Equation (10) may be rearranged to derive Equation (11) as follows:

$\begin{matrix}{d = {\frac{1}{\frac{1}{f} - \frac{1}{z}} = {\frac{fz}{z - f}.}}} & (11)\end{matrix}$

Inserting d from Equation (11) into (9) to show the striking pointresults in Equation (12) as follows:

$\begin{matrix}{{\left\lbrack {\frac{fz}{z - f} + z - \frac{\frac{fz}{z - f}z}{f}} \right\rbrack \theta} = {{\frac{{f^{2}z} + {fz}^{2} - {f^{2}z} - {fz}^{2}}{f\left( {z - f} \right)}\theta} = 0.}} & (12)\end{matrix}$

All rays leaving this point strike the focal plane at the optical axis.As shown in Equation (13), the situation when the cameras 63 and/or 65are shifted by a distance δ from the focus is described as follows:

$\begin{matrix}{{\left\lbrack {\frac{fz}{z - f} + \delta + z - \frac{\left\lbrack {\frac{fz}{z - f} + \delta} \right\rbrack z}{f}} \right\rbrack \theta} = {{\frac{{f^{2}z} + {{fz}\; \delta} - {f^{2}\delta} - {fz}^{2} - {f^{2}z} - {fz}^{2} - {\delta \; z^{2}} + {f\; \delta \; z}}{f\left( {z - f} \right)}\theta} = {{\frac{{fz} - f^{2} - z^{2} + {fz}}{f\left( {z - f} \right)}{\delta\theta}} = {{{- \frac{\left( {z - f} \right)^{2}}{f\left( {z - f} \right)}}{\delta\theta}} = {\frac{f - z}{f}{{\delta\theta}.}}}}}} & (13)\end{matrix}$

Equation (13) shows that by properly positioning the lens of the cameras63 and 64 with respect to the focal plane, we can change the depth offield. Additionally, the spot size depends upon the magnitude of theangle θ. This angle depends linearly on the aperture of the visionsystem created by the cameras 63 and/or 64.

Additionally or alternatively, in accordance with some embodiments ofthe present disclosure, cameras 63 and 64 may be implemented byadjusting for various parameters, including: the distance to the focusas it affects compactness, alignment, and sensitivity of the visionsystem to the environment; the field of view of the system; and thelens-focal plane separation as it affects the tolerances on alignment ofthe system and the sensitivity of the system to the environment.

FIG. 12 is a block diagram of an imaging system 78 of the cameras of thedrip-chamber holder of FIGS. 4 and 5 in accordance with an embodiment ofthe present disclosure. Although the camera 63 of FIGS. 4 and 5 willdescribed with reference to FIG. 12, camera 64 may also utilize theconfiguration described in FIG. 12.

FIG. 12 shows an imaging system 78 including a camera 63, a uniform backlight 70 to shine light at least partially through the drip chamber 59,and an infrared (“IR”) filter 80 that receives the light from theuniform back light 79. System 78 also includes a processor 90 that maybe operatively coupled to the camera 63 and/or the uniform back light79.

The uniform back light 79 may be an array of light-emitting diodes(“LEDs”) having the same or different colors, a light bulb, a window toreceive ambient light, an incandescent light, and the like. Inalternative embodiments, the uniform back light 79 may be replaced byone or more point-source lights.

The processor 90 may modulate the uniform back light 79 with the camera63. For example, the processor 90 may activate the uniform back light 79for a predetermined amount of time and signal the camera 63 to captureat least one image, and thereafter signal the uniform back light 79 toturn off. The one or more images from the camera 63 may be processed bythe microprocessor to estimate the flow rate and/or detect free flowconditions. For example, in one embodiment of the present disclosure,system 78 monitors the size of the drops being formed within the dripchamber 59, and counts the number of drops that flow through the dripchamber 59 within a predetermined amount of time; the processor 90 mayaverage the periodic flow from the individual drops over a period oftime to estimate the flow rate. For example, if X drops each having avolume Y flow through the drip chamber in a time Z, the flow rate may becalculated as (X*Y)/Z.

Additionally or alternatively, the system 78 may determine when the IVfluid is streaming through the drip chamber 59 (i.e. during a free flowcondition). The uniform back light 79 shines through the drip chamber 59to provide an image of the drip chamber 59 to the camera 63. The camera59 can capture one or more images of the drip chamber 59.

Other orientations of the system 78 may be used to account for thesensitivity and/or orientation of the uniform back light 79, the camera63, the characteristics of the light from the uniform back light 79, andthe ambient light. In some embodiments of the present disclosure, theprocessor 90 implements an algorithm that utilizes a uniformity of theimages collected by the camera 63 facilitated by the uniform back light79. For example, consistent uniform images may be captured by the camera63 when a uniform back light 79 is utilized.

Ambient lighting may cause inconsistencies in the images received fromthe camera 63, such as that caused by direct solar illumination.Therefore, in some embodiments of the present disclosure, an IR filter80 is optionally used to filter out some of the ambient light effects.For example, the IR filter 80 may be a narrow-band infrared light filterplaced in front of the camera 63; and the uniform back light 79 may emitlight that is about the same wavelength as the center frequency of thepassband of the filter 80. The IR filter 80 and the uniform back light79 may have a center frequency of about 850 nanometers. In alternativeembodiments, other optical frequencies, bandwidths, center frequencies,or filter types may be utilized in the system 78.

FIG. 13 is a graphic illustration of an image 81 captured by the camera63 of the system of FIG. 12, in accordance with an embodiment of thepresent disclosure. The image 81 shows condensation 82 and a stream 83caused by a free flow condition. Using edge detection may be used todetermine the position of the stream 83 and/or the condensation 82, insome embodiments. Additionally or alternatively, a background image orpattern may be used as described infra.

FIG. 14 is a block diagram of an imaging system 84 of the cameras of thedrip-chamber holder of FIGS. 4 and 5 in accordance with an embodiment ofthe present disclosure. Although the camera 63 of FIGS. 4 and 5 willdescribed with reference to FIG. 14, camera 64 may also utilize theconfiguration described in FIG. 14.

System 84 includes an array of lines 85 that are opaque behind the dripchamber 59. The array of lines 85 may be used in the detection of a freeflow condition of the system 84. The free flow detection algorithm mayuse the presence or absence of drops for determining whether or not astreaming condition, (e.g., a free flow condition) exists. Referring nowto FIG. 15, a graphic illustration of an image 86 is shown as capturedby the camera 63 of FIG. 14 when a free flow condition exists in thedrip chamber 59 in accordance with an embodiment of the presentdisclosure.

The image 86 illustrates the condition in which the drip chamber 59experiences a free flow condition and shows that the stream of fluid 87acts as a positive cylindrical lens. That is, as shown in FIG. 15, thearray of lines 85 as captured in an image by the camera 63 show areversed line pattern 88 from the array of lines 85 as compared to anon-free-flow condition.

In some embodiments of the present disclosure, an illumination of about850 nanometers of optical wavelength may be used to create the image 86.Some materials may be opaque in the visible spectrum and transparent inthe near IR at about 850 nanometers and therefore may be used to createthe array of lines 85. The array of lines 85 may be created usingvarious rapid prototyping plastics. For example, the array of lines 85may be created using a rapid prototype structure printed with aninfrared opaque ink or coated with a metal for making the array of lines85. Additionally or alternatively, in some embodiments of the presentdisclosure, another method of creating the array of lines 85 is tocreate a circuit board with the lines laid down in copper. In anotherembodiment, the array of lines 85 is created by laying a piece of ribboncable on the uniform back light 79; the wires in the ribbon cable areopaque to the infrared spectrum, but the insulation is transparent andthe spacing of the wires may be used for the imagining by the camera 63(see FIG. 14). In yet additional embodiments, a piece of thin electricdischarge machined metal may be utilized. Metal is opaque and the spacesof the material may very finely controlled during manufacturer to allowthe IR light to pass through the spaces.

The processor 90 implements an algorithm to determine when a free flowcondition exists. The processor 90 may be in operative communicationwith a computer readable medium 91 (e.g., a non-transitory computerreadable medium) to receive one or more instructions to implement thealgorithm to determine if a free flow condition exists. The one or moreinstructions from the computer readable medium 91 are configured forexecution by the processor 90.

Referring again to FIG. 14, blood may be used by the system 84. Forexample, system 84 may determine when a free flow condition of bloodexists when utilizing the camera 63, the IR filter 80, and the uniformback light 79 configured, for example, for use using optical lighthaving a wavelength of 850 nanometers or 780 nanometers, e.g., whenusing bovine blood. The blood may appear opaque compared to the imagerytaken using water as the fluid.

The following algorithm implemented by the processor 90 and receivedfrom the computer readable medium 91 may be used to determine when afree flow condition exists: (1) establish a background image 89 (seeFIG. 16); and (2) subtract the background image 89 from the currentimage. Additional processing may be performed on the resulting image.

In some embodiments of the present disclosure, the background image 89of FIG. 16 may be dynamically generated by the processor 90. The dynamicbackground image may be used to account for changing conditions, e.g.condensation or splashes 82 on the surface of the drip chamber (see FIG.13). For example, in one specific embodiment, for each new imagecaptured by the camera (e.g., 63 of FIG. 14), the background image haseach pixel multiplied by 0.96 and the current image (e.g., the mostrecently captured image) has a respective pixel multiplied by 0.04,after which the two values are added together to create a new value fora new background image for that respective pixel; this process may berepeated for all of the pixels. In yet another example, in one specificembodiment, if a pixel of the new image is at a row, x, and at a column,y, the new background image at row, x, and column, y, is the value ofthe previous background image at row, x, and column, y, multiplied by0.96, which is added to the value of the pixel at row, x, and column, yof the new image multiplied by 0.04.

When the system 84 has no water flowing through the drip chamber 59 (seeFIG. 14), the resulting subtraction should be almost completely black,i.e., low pixel magnitudes, thereby facilitating the algorithm todetermine that the drip chamber 59 has no water flowing therethrough.

FIG. 17 shows an image 92 from the camera 63 when there is a drop withinthe drip chamber 59 (see FIG. 14). FIG. 18 shows a background image 93used by the system 84. When the system 83 has a drop as shown in image92 of FIG. 17, the system 84 of FIG. 14 has a few high contrast-spotswhere the image of the array of lines is warped by the lensing of thedroplet as illustrated by an image 94 of FIG. 19. Image 94 of FIG. 19 isgenerated by taking, for each respective pixel, the absolute value ofthe subtraction of the image 92 of FIG. 92 from image 93 of FIG. 18, andconverting each respective pixel to a white pixel if the value is abovea predetermined threshold or otherwise converts the pixel to a blackpixel when the value is below the predetermined threshold. Each whitepixel within the image 94 of FIG. 19 is a result of there being adifference for that pixel location between the images 92 and 93 that isgreater than a predetermined threshold.

For example, consider three respective pixels of FIGS. 17, 18, and 19having a location of row, x, and column, y. To determine the pixel ofrow x and column y for the image 94 of FIG. 19, the pixel at row x andcolumn y of image 92 of FIG. 17 is subtracted from the pixel at row xand column y of image 92 of FIG. 18, then the absolute value of theresult of the subtraction is taken; and if the absolute value of theresult is above a predetermined threshold (e.g., above a grayscale valueof 128, for example), the pixel at the location of row x and column y ofimage 94 of FIG. 19 is white, otherwise the pixel at the location of rowx and column y of image 94 of FIG. 19 is black.

When it is determined that a few high contrast-spot exists within image94 of FIG. 19, the processor 90 of system 84 (see FIG. 14) determinesthat drops are being formed within the drip chamber 59 and no free flowcondition exists. The images of the drops may be utilized to determinetheir size to estimate a flow rate as described herein.

FIG. 20 is a graphic representation of some image processing that may beperformed using FIGS. 17-19 to determine if a free flow condition existsin accordance with an embodiment of the present disclosure. Referring toFIGS. 20 and 19, all of the white pixels for each row are summedtogether, and are illustrated in FIG. 20 as results 183. The y-axisrepresents the row number, and the x-axis represents the number of whitepixels determined for each respective row.

Referring now to only FIG. 20, as previously mentioned, the number ofwhite pixels for each row is summed together and is illustrated asresults 183, which are used to determine if or when a free flowcondition exists. In some specific embodiments, the processor 90 ofsystem 84 (see FIG. 14) determines that a free flow condition existswhen a predetermined number of contiguous values of the summed rows ofthe results 183 exist above a threshold 184. For example, within theresults 183, a plurality of rows represented generally by 185 have atotal value above the threshold 184. When greater than a predeterminednumber of contiguous summed rows are determined to exist within theresults 183, a free flow condition is determined to exist by theprocessor 90 of FIG. 14. For example, as shown in FIG. 20, the pluralityof contiguous rows 185 are below the predetermined number of contiguoussummed rows and therefore a free flow condition is determined to notexist.

FIG. 21 shows an image 95 showing a stream as captured by the camera 63of FIG. 14 when a free flow condition exists. FIG. 22 shows a backgroundimage 96. FIG. 23 shows an image 97 formed by the absolute value of thedifference between the image 96 of FIG. 22 and the image 95 from FIG. 21when the absolute value is converted either to a white pixel (when theabsolute value of the difference is above a threshold) or to a blackpixel (when the absolute value of the difference is below thethreshold). As shown in FIG. 23, high-contrast spots caused by thereverse orientation of the lines in the stream run from top to bottomare detectable by the processor 90. The processor 90 of FIG. 14 can usethe image 97 to determine if a free flow condition exists using thealgorithm described above.

That is, as shown in FIG. 24, results 186 are shown having a contiguousrange 187 of the results 186 that are above a threshold 188. Because thecontiguous range 187 of summed rows is greater than a predeterminedthreshold number of contiguous values above the threshold 188, a freeflow condition is determined to exist by the processor 90 (see FIG. 14).That is, the contiguous range of the results 186 above the threshold 188is greater than a predetermined threshold range of contiguous values;therefore, the processor 90 determines that a free flow condition existswhen using the results 186 of FIG. 24.

In yet an additional embodiment of the present disclosure, theintensity, the intensity squared, or other function may be used toproduce the results 183 and and/or 186. In yet an additional embodiment,one or more data smoothing functions may be used to smooth the results183 and/or 186, such as a spline function, cubic spline function,B-spline function, Bezier spline function, polynomial interpolation,moving averages, or other data smoothing functions.

For example, an image of the camera 63 of FIG. 14, e.g., image 95 ofFIG. 21, may be subtracted from a background image, e.g., the image 96of FIG. 22, to obtain intensity values. For example, a pixel of row xand column y of FIG. 21 may be subtracted from a pixel of row x andcolumn y of the image 96 of FIG. 22 to create an intensity value at rowx and column y; this may be repeated for all pixel locations to obtainall of the intensity values. The intensity values of each row may besummed together to obtain the results 183 and/or 186, such that theprocessor 90 may determine that a free flow condition exists when thesummed rows of the intensity values has a contiguous range of summedrows above a threshold. In some embodiments, the intensity values areconverted to an absolute value of the intensity values, and the summedrows of the absolute values of the intensity values are used todetermine if a contiguous range of summed rows of the absolute values isabove a threshold range of contiguous values. Additionally oralternatively, the intensity may be squared and then the processor 90may sum the squared intensity rows and determine if a contiguous rangeof summed rows of the intensity squared values exists beyond a thresholdrange of contiguous values to determine if a free flow condition exists.In some embodiments, a predetermined range of contiguous values above athreshold (e.g., min and max ranges) of the summed rows of intensityvalues or intensity squared values may be used by the processor 90 todetermine if a drop of liquid is within the image. For the rows of theintensity values (or the intensity squared values) may be summedtogether and a range of the summed values may be above a thresholdnumber; if the range of contiguous values is between a minimum range anda maximum range, the processor 90 may determine that the range ofcontiguous values above a predetermined threshold is from a drop withinthe field of view of the camera 63. In some embodiments of the presentdisclosure the summed rows of intensity values or intensity squaredvalues may be normalized, e.g., normalized to have a value between 0 and1.

The following describes a smoothing function similar to the cubic spline(i.e., the cubic-spline-type function) that may be used on the summedrows of intensity values or the summed rows of the intensity valuessquare prior to the determination by the processor 90 to determine if afree flow condition exits. The cubic-spline-type function may be used toidentify blocks as described below which may facilitate the processor's90 identification of free flow conditions, in some specific embodiments.

The cubic-spline-type function is an analog to the cubic spline, butsmoothes a data set rather than faithfully mimicking a given function.Having data sampled on the interval from [0,1] (e.g., the summationalong a row of intensity squared or intensity that is normalized) theprocessor 90 may find the best fit set of cubic functions on theintervals [x₀,x₁], [x₁,x₂], . . . , [x_(N−1),x_(N)] with and x₀=0 andx_(N)=1 where the total function is continuous with continuousderivatives and continuous curvature.

The standard cubic spline definition is illustrated in Equation (14) asfollows:

χ(x)=A _(i)(x)y _(i) +B _(i)(x)y _(i+1) +C _(i)(x)y _(i) ″+D _(i)(x)y_(i+1) ″ x _(i) ≤x≤x _(i+1)  (14),

with the functions A_(i), B_(i), C_(i), D_(i) defined as in the set ofEquations (15):

$\begin{matrix}{{{{A_{i}(x)} = {\frac{x_{i + 1} - x}{x_{i + 1} - x_{i}} = \frac{x_{i + 1} - x}{\Delta_{i}}}},{B_{i} = {\frac{x - x_{i}}{x_{i + 1} - x_{i}} = \frac{x - x_{i}}{\Delta_{i}}}}}{{{C_{i}(x)} = {\frac{\Delta_{i}^{2}}{6}\left( {{A_{i}^{3}(x)} - {A_{i}(x)}} \right)}},{D_{i} = {\frac{\Delta_{i}^{2}}{6}{\left( {{B_{i}^{3}(x)} - {B_{i}(x)}} \right).}}}}} & (15)\end{matrix}$

Equations (14) and (15) guaranty continuity and curvature continuity.The only values which can be freely chosen are the y_(i), y₀″ andy_(N)″. Please note that Equation (16) is chosen as follows:

y ₀ ″=y ₁″  (16),

i.e., the function is flat at 0 and 1. The remaining y_(i)″ must satisfythe following set of Equations (17):

$\begin{matrix}\begin{matrix}\begin{matrix}{{\frac{y_{1} - y_{0}}{\Delta_{0}} + \frac{y_{1}^{''}\Delta_{0}}{3}} = {\frac{y_{2} - y_{1}}{\Delta_{1}} - \frac{y_{1}^{''}\Delta_{1}}{3} - \frac{y_{2}^{''}\Delta_{1}}{6}}} \\{{\frac{y_{2} - y_{1}}{\Delta_{1}} + \frac{y_{1}^{''}\Delta_{1}}{6} + \frac{y_{2}^{''}\Delta_{1}}{3}} = {\frac{y_{3} - y_{2}}{\Delta_{2}} - \frac{y_{2}^{''}\Delta_{2}}{3} - \frac{y_{3}^{''}\Delta_{2}}{6}}} \\{{\frac{y_{3} - y_{2}}{\Delta_{2}} + \frac{y_{2}^{''}\Delta_{2}}{6} + \frac{y_{3}^{''}\Delta_{2}}{3}} = {\frac{y_{4} - y_{3}}{\Delta_{3}} - \frac{y_{3}^{''}\Delta_{3}}{3} - \frac{y_{4}^{''}\Delta_{3}}{6}}}\end{matrix} \\\vdots \\{{\frac{y_{N - 2} - y_{N - 3}}{\Delta_{N - 3}} + \frac{y_{N - 3}^{''}\Delta_{N - 3}}{6} + \frac{y_{N - 2}^{''}\Delta_{N - 3}}{3}} = {\frac{y_{N - 1} - y_{N - 2}}{\Delta_{N - 2}} - \frac{y_{N - 2}^{''}\Delta_{N - 2}}{3} - \frac{y_{N - 1}^{''}\Delta_{N - 2}}{6}}} \\{{\frac{y_{N - 1} - y_{N - 2}}{\Delta_{N - 2}} + \frac{y_{N - 2}^{''}\Delta_{N - 2}}{6} + \frac{y_{N - 1}^{''}\Delta_{N - 2}}{3}} = {\frac{y_{N} - y_{N - 1}}{\Delta_{N - 1}} - {\frac{y_{N - 1}^{''}\Delta_{N - 1}}{3}.}}}\end{matrix} & (17)\end{matrix}$

The set of Equations (17) can be rewritten as the set of Equations (18)as follows:

$\begin{matrix}\begin{matrix}\begin{matrix}{{{\frac{\Delta_{0} + \Delta_{1}}{3}y_{1}^{''}} + {\frac{\Delta_{1}}{6}y_{2}^{''}}} = {\frac{y_{0}}{\Delta_{0}} - {\left\lbrack {\frac{1}{\Delta_{0}} + \frac{1}{\Delta_{1}}} \right\rbrack y_{1}} + \frac{y_{2}}{\Delta_{1}}}} \\{{{\frac{\Delta_{1}}{6}y_{1}^{''}} + {\frac{\Delta_{1} + \Delta_{2}}{3}y_{2}^{''}} + {\frac{\Delta_{2}}{6}y_{3}^{''}}} = {\frac{y_{1}}{\Delta_{1}} - {\left\lbrack {\frac{1}{\Delta_{1}} + \frac{1}{\Delta_{2}}} \right\rbrack y_{2}} + \frac{y_{3}}{\Delta_{2}}}} \\{{{\frac{\Delta_{2}}{6}y_{2}^{''}} + {\frac{\Delta_{2} + \Delta_{3}}{3}y_{3}^{''}} + {\frac{\Delta_{3}}{6}y_{4}^{''}}} = {\frac{y_{2}}{\Delta_{2}} - {\left\lbrack {\frac{1}{\Delta_{2}} + \frac{1}{\Delta_{3}}} \right\rbrack y_{3}} + \frac{y_{4}}{\Delta_{3}}}}\end{matrix} \\\vdots \\{{{\frac{\Delta_{N - 4}}{6}y_{N - 3}^{''}} + {\frac{\Delta_{N - 3} + \Delta_{N - 2}}{3}y_{N - 2}^{''}} + {\frac{\Delta_{N - 2}}{6}y_{N - 1}^{''}}} = {\frac{y_{N - 3}}{\Delta_{N - 3}} - {\left\lbrack {\frac{1}{\Delta_{N - 3}} + \frac{1}{\Delta_{N - 2}}} \right\rbrack y_{N - 2}} + \frac{y_{N - 1}}{\Delta_{N - 2}}}} \\{{{\frac{\Delta_{N - 1}}{6}y_{N - 2}^{''}} + {\frac{\Delta_{N - 2} + \Delta_{N - 1}}{3}y_{N - 1}^{''}}} = {\frac{y_{N - 2}}{\Delta_{N - 2}} - {\left\lbrack {\frac{1}{\Delta_{N - 2}} + \frac{1}{\Delta_{N - 1}}} \right\rbrack y_{N - 1}} + {\frac{y_{N}}{\Delta_{N - 1}}.}}}\end{matrix} & (18)\end{matrix}$

In turn, this becomes the matrix Equation (19):

$\begin{matrix}{{\begin{bmatrix}\frac{\Delta_{0} + \Delta_{1}}{3} & \frac{\Delta_{1}}{6} & 0 & \; & 0 & 0 & 0 \\\frac{\Delta_{1}}{6} & \frac{\Delta_{1} + \Delta_{2}}{3} & \frac{\Delta_{2}}{6} & \ldots & 0 & 0 & 0 \\0 & \frac{\Delta_{2}}{6} & \frac{\Delta_{2} + \Delta_{3}}{3} & \; & 0 & 0 & 0 \\\; & \vdots & \; & \ddots & \; & \vdots & \; \\0 & 0 & 0 & \; & \frac{\Delta_{N - 4} + \Delta_{N - 3}}{3} & \frac{\Delta_{N - 3}}{6} & 0 \\0 & 0 & 0 & \ldots & \frac{\Delta_{N - 3}}{3} & \frac{\Delta_{N - 3} + \Delta_{N - 2}}{3} & \frac{\Delta_{N - 2}}{6} \\0 & 0 & 0 & \; & 0 & \frac{\Delta_{N - 2}}{6} & \frac{\Delta_{N - 2} + \Delta_{N - 1}}{3}\end{bmatrix}\begin{Bmatrix}y_{1}^{''} \\y_{2}^{''} \\y_{3}^{''} \\\vdots \\y_{N - 3}^{''} \\y_{N - 2}^{''} \\y_{N - 1}^{''}\end{Bmatrix}} = {\quad{\begin{bmatrix}\frac{1}{\Delta_{0}} & {{- \frac{1}{\Delta_{0}}} - \frac{1}{\Delta_{1}}} & \frac{1}{\Delta_{1}} & \; & 0 & 0 & 0 \\0 & \frac{1}{\Delta_{1}} & {{- \frac{1}{\Delta_{1}}} - \frac{1}{\Delta_{2}}} & \ldots & 0 & 0 & 0 \\0 & 0 & \frac{1}{\Delta_{2}} & \; & 0 & 0 & 0 \\\; & \vdots & \; & \ddots & \; & \vdots & \; \\0 & 0 & 0 & \; & \frac{1}{\Delta_{N - 3}} & 0 & 0 \\0 & 0 & 0 & \ldots & {{- \frac{1}{\Delta_{N - 3}}} - \frac{1}{\Delta_{N - 2}}} & \frac{1}{\Delta_{N - 2}} & 0 \\0 & 0 & 0 & \; & \frac{1}{\Delta_{N - 2}} & {{- \frac{1}{\Delta_{N - 2}}} - \frac{1}{\Delta_{N - 1}}} & \frac{1}{\Delta_{N - 1}}\end{bmatrix}\begin{Bmatrix}y_{0} \\y_{1} \\y_{2} \\y_{3} \\\vdots \\y_{N - 3} \\y_{N - 2} \\y_{N - 1} \\y_{N}\end{Bmatrix}}}} & (19)\end{matrix}$

The set of Equations (19) may be rewritten as the set of Equations (20):

Fy _(dd) =Gy

y _(dd) =F ⁻¹ Gy=Hy  (20).

Choosing the values in the vector y using a least squares criterion onthe collected data is shown in Equation (21) as follows:

E=Σ[ψ _(k) −A _(i) _(k) (ξ_(k))y _(i) _(k) −B _(i) _(k) (ξ_(k))y _(i)_(k) ₊₁ −C _(i) _(k) (ξ_(k))y _(i) _(k) ″−D _(i) _(k) (ξ_(k))y _(i) _(k)″]²  (21).

That is, Equation (21) is the minimum deviation between the data and thespline, i.e., an error function. The y values are chosen to minimize theerror as defined in Equation 21; The vector of predicted values can bewritten as illustrated in Equation (22) as follows:

$\begin{matrix}\begin{matrix}{\hat{y} = {{\left( {A_{\{ k\}} + B_{\{ k\}}} \right)y} + {\left( {C_{\{ k\}} + D_{\{ k\}}} \right)y_{dd}}}} \\{= {{\left( {A_{\{ k\}} + B_{\{ k\}}} \right)y} + {\left( {C_{\{ k\}} + D_{\{ k\}}} \right){Hy}}}} \\{= {\left\lbrack {A_{\{ k\}} + B_{\{ k\}} + {C_{\{ k\}}H} + {D_{\{ k\}}H}} \right\rbrack y}} \\{{= {Ay}},}\end{matrix} & (22)\end{matrix}$

The elements of the matrix in brackets of Equation (22) depend upon thex-value corresponding to each data point, but this is a fixed matrix.Thus the final equation can be determined using the pseudo-inverse. Inturn, the pseudo-inverse only depends upon the x-locations of the dataset and the locations where the breaks in the cubic spline are set. Theimplication of this is that once the geometry of the spline and the sizeof the image are selected, the best choice for the y given a set ofmeasured values y_(m) is illustrated in Equation (23) as follows:

y=(A ^(T) A)⁻¹ A·y _(m)  (23).

The cubic spline through the sum intensity-squared function of the imagewill then be given by Equation (24):

y _(cs) =A·y  (24).

Because we will want to find the maximum values of the cubic spline, wewill also need the derivative of the spline. The cubic spline derivativeis given by Equation (25) as follows:

$\begin{matrix}\begin{matrix}{{\chi^{\prime}\left( x_{k} \right)} = {{{A_{i_{k}}^{\prime}\left( x_{k} \right)}y_{i_{k}}} + {{B_{i_{k}}^{\prime}\left( x_{k} \right)}y_{i_{k} + 1}} + {{C_{i_{k}}^{\prime}\left( x_{k} \right)}y_{i_{k}}^{''}} + {{D_{i_{k}}^{\prime}\left( x_{k} \right)}y_{i_{k} + 1}^{''}}}} \\{= {{- \frac{y_{i_{k}}}{\Delta_{i_{k}}}} + \frac{y_{i_{k} + 1}}{\Delta_{i_{k}}} - {\frac{\Delta_{i_{k}}y_{i_{k}}^{''}}{6}\left( {{3{A_{i_{k}}^{2}\left( x_{k} \right)}} - 1} \right)} +}} \\{{\frac{\Delta_{i_{k}}y_{i_{k} + 1}^{''}}{6}{\left( {{3{B_{i_{k}}^{2}\left( x_{k} \right)}} - 1} \right).}}}\end{matrix} & (25)\end{matrix}$

Equation (25) can be written as Equation (26):

$\begin{matrix}\begin{matrix}{y_{cs}^{\prime} = {{\left( {A_{\{ k\}}^{\prime} + B_{\{ k\}}^{\prime}} \right)y} + {\left( {C_{\{ k\}}^{\prime} + D_{\{ k\}}^{\prime}} \right)y_{dd}}}} \\{= {\left\lbrack {A_{\{ k\}}^{\prime} + B_{\{ k\}}^{\prime} + {C_{\{ k\}}^{\prime}H} + {D_{\{ k\}}^{\prime}H}} \right\rbrack y}} \\{= {A^{\prime}{y.}}}\end{matrix} & (26)\end{matrix}$

Once the current values of y are found, the cubic spline, y_(cs), andits derivative, y′_(cs) can be calculated. The cubic spline data mayinclude “blocks” of data that includes values above a predeterminedthreshold. A pipe block is formed by the liquid flowing out of the tubeinto the drip chamber 59 and a pool block is formed as the liquidcollects at the gravity end of the drip chamber 59 (see FIG. 14).

The following algorithm may be applied to the cubic spline data: (1)determine the local maxima of the cubic spline data using the derivativeinformation; (2) determine the block surrounding each local maxima byincluding all points where the cubic spline value is above a thresholdvalue; (3) merge all blocks which intersect; (4) calculate informationabout the block of data including the center of mass (intensity), thesecond moment of the mass (intensity), the lower x-value of the block,the upper x-value of the block, the mean value of the original sum ofintensity squared data in the block, the standard deviation of theoriginal sum of intensity squared data in the block, and the meanintensity of a high-pass filtered image set in the block; and (5)interpret the collected data to obtain information about when dropsoccur and when the system is streaming.

The mean intensity of a high-pass filtered image set in the block isused to determine if the block created by each contiguous range ofspline data is a result of a high frequency artifact (e.g., a drop) or alow frequency artifact. This will act as a second background filterwhich tends to remove artifacts such as condensation from the image.That is, all previous images in an image memory buffer (e.g., 30previous frames, for example) are used to determine if the data is aresult of high frequency movement between frames. If the block is aresult of low frequency changes, the block is removed, or if it is aresult high frequency changes, the block is kept for further analysis. Afinite impulse response filter or an infinite impulse response filtermay be used.

Each block is plotted over its physical extent with height equal to themean value of the data within the block. If a block has a mean value ofthe high-pass filter image less than the threshold, it is an indicationthat it has been around for several images and thus may be removed.

Free flow conditions may be determined by the processor 90 to existusing the blocks when the pipe block extends nearly to the pool block,the pipe block and the pool block merge together, and/or the summedrange of widths of the pool and pipe blocks (or all blocks) is greaterthan a predetermined threshold, e.g., the total extent of the blocksexceeds 380 pixels in width. The processor 90 may detect a drop when thetransition of the pipe block from a larger width to a shorter widthoccurs as a result of a drop formation in the tube and as the dropleaves the pipe (i.e., tube) opening of the drip chamber 59. Theprocessor 90 may detect this by looking at the ratio of the current pipeblock width to the previous image's pipe block width, e.g., an imagewhere the ratio is less than 0.9 while simultaneously is a local minimais may be considered by the processor 90 to be an image formedimmediately after a drop has formed.

Various filtering algorithms may be used to detect condensation or otherlow frequency ratification, such as: If a block has a low mean value inthe high-pass filter image, then it may be condensation. This artifactcan be removed from consideration. Additionally or alternatively, longblocks (e.g., greater than a predetermined threshold) with a lowhigh-pass mean value are possibly streams, since stream images tend toremain unchanging.

The processor 90 may, in some specific embodiments use the block data tocount the drops thereby using the system 84 as a drop counter. Theprocessor 90 may also use width changes in the pool block as a dropdisturbs the water to determine if a bubble formed with the drop hit thepool. For example, the processor 90 may determines that a block formsbelow the pool block, then the processor 90 may determine that a bubbleformed when a drop hit the water. The bubble may be filtered out by theprocessor 90 to determine if a predetermined value of total block rangesindicates that a free flow condition exists.

In some embodiments of the present disclosure, the depth of field of thesystem 84 may have a narrow depth of field to make the system 84 lesssensitive to condensation and droplets on the chamber walls. In someembodiments, a near focus system may be used.

Referring now to FIG. 25, in another embodiment of the presentdisclosure a template 189 is used to determine if a free flow conditionexists. The template 189 is used by the processor 90 of FIG. 14 todetermine a pattern match score 190. The image 94 of FIG. 19 may becompared against the pattern 189 (e.g., a difference between abackground image and an image captured by the camera 63 of FIG. 14 whichis then converted to either a black pixel if the difference is below athreshold value or a white pixel if the difference is above a thresholdvalue). If the pattern match score 190 is above a predeterminedthreshold, a free flow condition is determined to exist. The templatematching may utilize a template matching algorithm as found in OpenSource Computer Vision (“OpenCV”) library. For example, the template 189may be used with the matchTemplate( ) function call of the OpenCVlibrary using the CV_TM_CCOEFF method or the method ofCV_TM_CCOEFF_NORMED. The CV_TM_CCOEFF method uses the pattern matchingalgorithm illustrated in Equation (27) as follows:

$\begin{matrix}{{{R\left( {x,y} \right)} = {\sum\limits_{x^{\prime},y^{\prime}}^{\;}\left( {{T^{\prime}\left( {x^{\prime},y^{\prime}} \right)} \cdot {I^{\prime}\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}} \right)}},} & {(27),}\end{matrix}$

where:

T′(x′,y′)=T(x′,y′)−1/(w·h)·Σ_(x″,y″) T(x″,y″)

I′(x+x′,y+y′)=I(x+x′,y+y′)−1/w·h)·Σ_(x″,y″) I(x+x″,y+y″)

The I denotes the image, the T denotes the template, and the R denotesthe results. The summation is done over the template and/or the imagepatch, such that: x′=0 . . . w−1 and y′=0 . . . h−1.

The results R can be used to determine how much the template T ismatched at a particular location within the image I as determined by thealgorithm. The OpenCV template match method of CV_TM_CCOEFF_NORMED usesthe pattern matching algorithm illustrated in Equation (28) as follows:

$\begin{matrix}{{R\left( {x,y} \right)} = {\frac{\sum\limits_{x^{\prime},y^{\prime}}^{\;}\left( {{T^{\prime}\left( {x^{\prime},y^{\prime}} \right)} \cdot {I^{\prime}\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}} \right)}{\sqrt{\sum\limits_{x^{\prime},y^{\prime}}^{\;}{{T^{\prime}\left( {x^{\prime},y^{\prime}} \right)}^{2} \cdot {\sum\limits_{x^{\prime},y^{\prime}}^{\;}{I^{\prime}\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}^{2}}}}}.}} & (28)\end{matrix}$

In another embodiment of the present disclosure, the template matchingalgorithm uses a Fast Fourier Transform (“FFT”). In some embodiments,any of the methods of the matchTemplate( ) function of OpenCV may beused, e.g., CV_TM_SQDIFF, CV_TM_SQDIFF_NORMED, CV_TM_CCORR, and/orCV_TM_CCORR_NORMED.

The CV_TM_SQDIFF uses the pattern matching algorithm illustrated inEquation (29) as follows:

$\begin{matrix}{{R\left( {x,y} \right)} = {\sum\limits_{x^{\prime},y^{\prime}}^{\;}{\left( {{T\left( {x^{\prime},y^{\prime}} \right)} - {I\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}} \right)^{2}.}}} & (29)\end{matrix}$

CV_TM_SQDIFF_NORMED uses the pattern matching algorithm illustrated inEquation (30) as follows:

$\begin{matrix}{{R\left( {x,y} \right)} = {\frac{\sum\limits_{x^{\prime},y^{\prime}}^{\;}\left( {{T\left( {x^{\prime},y^{\prime}} \right)} - {I\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}} \right)^{2}}{\sqrt{\sum\limits_{x^{\prime},y^{\prime}}^{\;}{{T\left( {x^{\prime},y^{\prime}} \right)}^{2} \cdot {\sum\limits_{x^{\prime},y^{\prime}}^{\;}{I\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}^{2}}}}}.}} & (30)\end{matrix}$

CV_TM_CCORR uses the pattern matching algorithm illustrated in Equation(31) as follows:

$\begin{matrix}{{R\left( {x,y} \right)} = {\sum\limits_{x^{\prime},y^{\prime}}^{\;}{\left( {{T\left( {x^{\prime},y^{\prime}} \right)} \cdot {I\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}} \right).}}} & (31)\end{matrix}$

CV_TM_CCORR_NORMED uses the pattern matching algorithm illustrated inEquation (32) as follows:

$\begin{matrix}{{R\left( {x,y} \right)} = {\frac{\sum\limits_{x^{\prime},y^{\prime}}^{\;}\left( {{T\left( {x^{\prime},y^{\prime}} \right)} \cdot {I^{\prime}\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}} \right)}{\sqrt{\sum\limits_{x^{\prime},y^{\prime}}^{\;}{{T\left( {x^{\prime},y^{\prime}} \right)}^{2} \cdot {\sum\limits_{x^{\prime},y^{\prime}}^{\;}{I\left( {{x + x^{\prime}},{y + y^{\prime}}} \right)}^{2}}}}}.}} & (32)\end{matrix}$

In yet another embodiment of the present disclosure, a template of agrayscale image of a free flow condition is compared to an image takenby the camera 63 of FIG. 14 to determine if a free flow conditionexists. In some embodiments, the template matching function within theOpenCV library may be utilized.

Refer now to FIGS. 26 and 27; in yet an additional embodiment of thepresent disclosure, the algorithm to determine when a free flowcondition exists being executed on the processor 90 of FIG. 14 mayutilize an algorithm to determine if a template pattern matches an arrayof pixels utilizing edge detecting followed by line detection. As shownin FIG. 26, an image 98 is formed from an image 99 of FIG. 27, by usingedge detected followed by line detection. The resulting lines may beutilized by the processor 90 to determine that a free flow conditionexists. As shown in FIG. 26, the feature which shows up after thisprocessing by the processor 90 are lines that have a different slopethan the expected 45° slope of the background reference image. The lineshaving the angle of the background image may be filtered out of FIG. 26,in some embodiments. The lines may be detected as edges using a Cannyalgorithm as found in the OpenCV library with the Hough algorithm todetermine the slope of the lines also found in the OpenCV library.

FIGS. 28-32 illustrate various background patterns that may be used todetect a free flow condition or estimate the size of a drop of liquid.When used with the back patterns of FIGS. 28-32, the cameras 102mentioned for use in FIGS. 28-32 may be the cameras 63 or 64 of FIG. 4or 5, the camera of FIG. 6, the camera 63 of FIG. 14 each of which maybe coupled to a respective processor for processing the images from thecamera, such as processor 75 of FIG. 6 or the processor 90 of FIG. 14.

FIG. 28 is a block diagram of an imaging system 100 for use with thedrip-chamber 104 (e.g., a drip chamber as found in the drip-chamberholder of FIGS. 4-5 or FIG. 6) having a back pattern 101 with stripesand a light source 102 shining on the stripes from an adjacent locationto a camera 103 in accordance with an embodiment of the presentdisclosure. Any drops or free flow streams within the drip chamber 104distorts the image taken by the camera 103. A processor coupled to thecamera 103 (e.g., processor 75 of FIG. 6) can use the distortions of theback pattern 101 as captured by the camera 103 to estimate flow rateand/or detect free flow conditions.

FIG. 29 is a block diagram of an imaging system 105 for use with thedrip-chamber 104 having a back pattern 101 with stripes and a lightsource 102 shining on the stripes from behind the back pattern 101relative to an opposite end to a camera 103 in accordance with anembodiment of the present disclosure. FIG. 30 shows an image from thecamera 103 of FIG. 29 when a drop distorts the back pattern 101 of FIG.29 in accordance with an embodiment of the present disclosure. Note thatas shown in FIG. 30, the back pattern's 101 stripes are distorted by adrop (or will be distorted by a free flow stream) from the drip chamber104 as captured in images by the camera 103. This distortion may be usedto estimate the drop size, to calculate the flow rate through afluid-chamber holder, or to determine if a free flow condition exists.

FIG. 31 is a block diagram of an imaging system for use with thedrip-chamber holder of FIGS. 4-5 or FIG. 6 having a back pattern with acheckerboard pattern and a light source shining on the stripes frombehind the back pattern relative to an opposite end to a camera inaccordance with an embodiment of the present disclosure. FIG. 32 showsan image from the camera of FIG. 31 when a drop distorts the backpattern 107 of FIG. 26 in accordance with an embodiment of the presentdisclosure. In yet another embodiment, the background may be formedusing a plurality of random dots and/or circles.

Referring to FIGS. 28-32, the Lensing of a drop (i.e., the distortion ofthe back pattern from the view of a camera) may be used to measure theradius of the drop. The radius of the drop is related to the effect ithas on the light passing through it. By measuring the change to thecalibration grid as seen through the drop, the radius and hence thevolume of the drop can be calculated. For example, the magnification ofa test grid of known size as seen through the drop could be measuredoptically and the radius inferred from this measurement. Therelationship between the radius and the drop may be calculated and/ormay be determined using a lookup table that has been generatedempirically.

FIG. 33 shows a block diagram of an air detector 108 using a camera 109in accordance with an embodiment of the present disclosure. The airdetector 108 may be the air detector 24 of FIG. 1, the air detector 410of FIG. 2 or FIG. 3, or the air detector 65 of FIG. 5. Additionally oralternatively, in some specific embodiments, the air detector 108 may beformed within the drip-chamber holder 58 and the camera 109 may be thecamera 65 of the drip-chamber holder 58 (see FIGS. 4 and 5).

The air detector 108 includes the camera 109, a backlight 110, aprocessor 584, and a memory 585. The backlight 110 shines light throughthe tube 111. The camera may optionally include an IR filter on its lensand/or the backlight may be tuned to an infrared wavelength orbandwidth, e.g., to correspond to the IR filter.

The camera 109 may be operatively coupled to one or more processors 584that are in operative communication with a computer readable memory 585,e.g., RAM, ROM, disk, hard disk, memory, etc. The computer readablememory 585 may include one or more operative instructions configurationfor execution by the one or more processor. The one or more operativeinstructions may implement an algorithm to detect or determine thepresent of air within the tube 111; for example, by determining ordetecting the presence of one or more bubbles within the tube 111.

Additionally or alternatively, the system 108 can be used to detect thestatus of the tube 111 designed to transport fluid, e.g., in thisexample IV tubing. The camera 109 may be a digital camera that capturesimages of the tube 111 that is back-lit with a diffuse light from abacklight 110. The backlight 110 may consist of a clear plastic materialedge-lit with a set of LEDs (e.g., as is used on a liquid crystaldisplay). The camera 109 may capture one or more images so that the oneor more processors can detect or determine the following: (1) if thetube 111 has been installed in the device; (2) if the tube 111 has beenprimed (i.e., is full of liquid); (3) if there are bubbles in the tube;and/or (4) the color and opacity of the fluid in the tube.

Referring now to FIGS. 34, 35, and 36 for a description of an exemplaryuse of the system 108 of FIG. 33. The detection algorithm residingwithin the memory 585 and executed by the processor 584 (see FIG. 33)uses three template images: one representing no tube installed; anotherrepresenting a tube installed with clear liquid therein; and anotherrepresenting a thin vertical slice of a bubble as shown in FIG. 34. Thealgorithm quantifies how closely each section of the tube 111 matchesthe bubble template of FIG. 34, the no tube template, or the tubetemplate with liquid therein. The matching algorithm may utilize theOpenCV pattern matching function, matchTemplate( ) described in Equation(14) or Equation (15) above, or an FFT pattern matching algorithm. Inyet additional embodiment any of the methods for pattern matching of thematchTemplate( ) of openCV may be used, such as, for example,CV_TM_SQDIFF, CV_TM_SQDIFF_NORMED, CV_TM_CCORR, and/orCV_TM_CCORR_NORMED.

The pattern matching algorithm may scan from one side to the other side,e.g., from left to right. As the processor 584 scans across the image,the pattern matching algorithm tries to match each template to one ofthe scanned section. If a template matches, and several scans later, notemplate is matched and finally another template is matched, theprocessor may interpolate that the later template is the most likely onethat should have been matched. For example, when scanning from left toright, in region 191, the template of a tube with liquid thereinmatches. When transitioning from a side of the bubble 112 from the left,a region 194 on the left side of the bubble within the box 112 may notmatch any template, and finally, within the box 112, the bubble maymatch to the air template in region 193; the processor 584 may assumethe reason the pattern matching algorithm could not match theintermediate region of 194 with a template is because the bubble's imagestarted to change the camera's view. Therefore, in this example, theregion 194 in which no template was determined to match, the processor584 may assume that the bubble was present. Also note that interpolationmay be used in region 195.

If there is a close match (including the interpolation as describedabove) a bubble can be identified as is shown in the box 112. The sizeof the bubble in the box 112 can be estimated based on the tube's 111diameter (either known in advanced or measured by the camera 109 of FIG.33) and the bubble length found in the template matching algorithm,e.g., as determined by the box 112. The box 112 may model the bubble asa cylinder having the diameter of the tube 111. The bubble informationcan be compared frame to frame to keep track of how many bubbles havemoved through the field of view and their sizes (and thus the totalamount of air delivered to a patient may be tracked). The processor 584may issue an alert or alarm if any bubble exceeds a given size, if thetotal amount of air passing through the tube 111 exceeds a predeterminedthreshold, or if the total amount of air passing through the tube 111exceeds a predetermined threshold within a predetermined amount of time.In some embodiments, the color of the fluid may be used to estimateand/or determine the amount of air dissolved within the liquid withinthe tube 111.

In some embodiments, the bubble of FIG. 36 may have its shape estimated.For example, edge detection may be used to identify the left and rightedges of the bubble to estimate its volume, e.g., Canny edge detection,a first-order edge detection algorithm, a second-order edge detectionalgorithm, a phase congruency-based edge detection algorithm, and thelike. The edge detection algorithm may utilize one found in OpenCV.Additionally or alternatively, the edge detection algorithm may average5 previous pixels from a side (e.g., the left side) and compare that toan average of the next 5 pixels (e.g., the right side), and when thechange exceeds a predetermined threshold, the edge of the bubble may bedetermined to be present.

Additionally or alternatively, the camera 109 can capture an image witha threshold amount of red liquid within the tube 111 such that the oneor more processors 584 determines that blood is present within the tube111. For example, the system 108 having the camera 109 of FIG. 33 may beused to form the infiltration detector 32 of FIG. 2. One or more of thepumps, e.g., pumps 19, 20, and 21, may be used to create a backpressureto determine if the catheter is properly in the vein. That is, if thecatheter is properly within the vein, then a small amount of negativepressure within the tube should draw blood into the tube. As shown inFIG. 37, blood 113 may be captured within an image taken by the camera109 of FIG. 33, which is then processed to determine that a threshold ofred exists. FIG. 38 shows a region 114 determined by the one or moreprocessors, e.g., processor 37 of FIG. 2, that a threshold amount of redcolor exists. The white pixels depicts that a threshold amount of redhas been detected and a black pixel depicts that a threshold amount ofred has not been detected for that pixel.

In another embodiment, the pixels are converted to grayscale and then athreshold amount of a dark color may be used to determine that bloodexists at each individual pixel. For example, if the pixel is determinedto be below a threshold (e.g., closer to black beyond a threshold), thatpixel may be determined to be blood and is thereby converted to whitewhile the remaining pixels are converted to black (or in otherembodiments, vice versa). For example, the image taken may be in RGBformat which is then converted to a grayscale image using the voidcvtColor( ) function of the OpenCV library using the CV_RGB2GRAY_colorspace conversion code. The threshold amount may be 50, 128, or may bedynamically adjusted.

The processor 37 may determine that infiltration has occurred when theinfusion site monitor 26 of FIG. 2 receives no blood or less than apredetermined amount of blood within the tube when a predeterminedamount of negative pressure is present within the tube, e.g., whenrunning an infusion pump in reverse. The amount of blood may bedetermined by summing the white pixels within the region 114. The tubemay include fiducials to help locate the tube and/or the tube's holder.Additionally or alternatively, fiducials may be used to indicatedistance, e.g., the volume of blood in the tube may be correlated withthe length of the blood within the tube using the fiducials, forexample, to prevent drawing back too much blood during an infiltrationtest.

FIG. 39 shows an infiltration detector 115 in accordance with anembodiment of the present disclosure. The infiltration detector 115 ofFIG. 39 may be the infiltration detector 32 of FIG. 2. The infiltrationdetector 115 includes a photodiode coupled to a T-connector 117. TheT-connector connects the tube 118 to the tube 119 that feeds liquid intothe view 120 via an internal portion of the catheter 121. Theinfiltration detector 115 also includes an LED 122 that shines lightinto the skin 124. The photodiode 116 and the LED 122 may be coupled toa processor that implements an algorithm to determine when infiltrationhas occurred, e.g., processor 37 of the infusion site monitor 26 of FIG.2. The algorithm may be implemented by an operative set of processorexecutable instructions (e.g., as stored on a memory 38) configured forexecution by the processor (e.g., the processor 37).

Blood entering into the tube 119 and found around the catheter hassignificant light absorbing properties at specific wavelengths thatwould minimize the passage of light from the LED 122 through a lightpath that passes through soft tissue, the vein wall, venous blood, andthe fluid in the IV catheter and tubing 119. When infiltration hasoccurred, fluid should surround the internal portion of the catheter 121(e.g., 18 Gauge), and the amount of light from the LED 122 to thephotodiode 116 is reduced from optical absorption caused by the blood.This is in contrast to an infiltrated state where IV fluid surroundingthe catheter 121 minimally absorbs or attenuates the same lightwavelength absorbed by venous blood and therefore allows a largerintensity of light to pass from the LED 122, through the soft tissue,extravasated fluid, and then into the catheter 121 and IV tubing 119 tothe light detector, e.g., the photodiode 116.

The photodiode 116 may be disposed such that it could receive any lightpassing through a catheter 121 and the tube 119. The T-connector 117 isconfigured to allow fluid to simultaneously pass into the catheter 121from tube 118 via tube 119, and allow light from the tube 119 to bediverted into the photodiode 116.

The LED 122 emits light at a wavelength that is attenuated by thehemoglobin in the blood and is positioned to illuminate the surface ofthe skin 124 near the open end of the catheter 121. When the catheter121 is properly placed within the vein 126, the attenuation of theillumination from the LED 122 by blood reduces the amount of light thatreaches the photodiode 116. Additionally, when the catheter 121 is nolonger positioned within the vein 126 (e.g., which occurs when aninfiltration occurs), the illumination from the LED 122 passes into thecatheter 121 and through the tube 119 to be detected by the photodiode116.

FIG. 40 shows a graphic 127 illustrating the optical absorption ofoxygenated and de-oxygenated hemoglobin in accordance with an embodimentof the present disclosure. The graphic 127 shows that both oxygenatedand de-oxygenated hemoglobin have strong absorption in the 530-590nanometer range and the 400-450 nanometer range. Referring again to FIG.39, in some embodiments of the present disclosure, the LED 122 and thephotodiode 116 may be configured to emit and absorb, respectively, 405nanometers, 470 nanometers, 530 nanometers, 590 nanometers and 625nanometers optical wavelengths. In some embodiments, the photodiode 116may be a silicon photo-detector with measurable response from 400nanometers to 1000 nanometers.

Referring now to FIG. 41, another infiltration detector 128 inaccordance with another embodiment of the present disclosure is shown.The infiltration detector 128 includes a laser 129 to further illuminatethe vein 126. The photodiode 116 is placed at the end of a syringe 130,which includes a wrapping of copper tape to minimize stray light. TheLED 122, the laser 129 (e.g., a laser pointer), or both may be used toilluminate the end of the catheter 121. The LED 122 may emit lighthaving wavelengths about 625 nanometers, and the laser 129 may emitlight red wavelengths.

In some embodiments of the present disclosure, the catheter 121 and/orthe tube 119 includes a stainless steel needle (e.g., 18 gauge) havingconnectors wrapped in aluminum foil. In yet additional embodiments ofthe present disclosure, the LED 122 and/or the laser 129 may bemodulated to enhance detection by the photodiode 116.

The syringe 130 may be used to apply a negative pressure to the tube119. The processor 37 of FIG. 2 may be coupled to the photodiode 116 anda position sensor of the syringe 130 to determine if an infiltration hasoccurred. If, after the syringe 130 (either manually of via an automaticactuator) is pulled back as sufficient amount of distance and no bloodis detected by the photodiode 116 (e.g., from spectral absorption by theblood), the processor 37 may issue an alert and/or alarm to indicatethat an infiltration has occurred.

In another embodiment, a small fiber optic disposed through the catheter121 or needle illuminates the area at the tip of the catheter 121, e.g.,the LED 122 is coupled to the fiber optic cable to guide light into thevein 126. Additionally or alternatively, a pulse oximeter over the IVsite may be used to automatically measure a baseline profile ofabsorption to detect changes caused by an infiltration, e.g., using theprocessor 37.

It yet additional embodiments, a fluorescent coating is optionallyapplied to the tip of the needle of the catheter 121 that is excitableby light in a wavelength significantly absorbed by venous blood. Forexample, colored light which is absorbed by hemoglobin would not bedetectable when the catheter 121 is properly located in the vein. Whenthe catheter 121 was located outside of the vein, this light would notbe absorbed and would become detectable by the photodiode 116. Thefluorescent coating will emit less when the exciting light is absorbedby the hemoglobin, and the emitted light may also be absorbed by thehemoglobin.

For example, the emitted light from the fluorescent coating may bedifferent than the exciting light, e.g., from the LED 122, and thephotodiode 116 may include a filter to filter out the exciting lightfrom the LED 122 and to receive the light being emitted from the excitedfluorescent coating. In some embodiments, the fluorescent coating mayfluoresce when a black light is applied. Additionally or alternatively,the LED 122 may be modulated.

FIG. 42 shows a perspective view of an occluder 131 in accordance withan embodiment of the present disclosure. FIG. 43 shows a side view ofthe occluder 131, and FIG. 44 shows a side view of the occluder 131 inoperation. Referring now to all of FIGS. 42, 43, and 44, the occluder131 includes occluder edges 132 and a pivot 133. The occluder 131 mayinclude a spring (not shown) to force the occlude edges 132 against atube 135. Additionally or alternatively, the occluder 131 may include anactuator 134 to actuate the occluder 131 against the tube 134.

The occluder 131 may be used within a peristaltic pump such that when adoor is opened for positioning the tube 135, the occluder 131 is openedfor placing the tube 135 within the region of the occluder edges 132.When the door is opened again, the occluder 131 may transition from anopen to a relaxed state by action of the actuator 134 to occlude thetube 135.

FIG. 45 shows a side view of a valve 136 for use in a cassette inaccordance with an embodiment of the present disclosure; FIG. 46 shows atop view of the valve 136; and FIG. 47 shows another side view of thevalve 136 installed within a cassette in accordance with an embodimentof the present disclosure. As is easily seen in FIG. 45, a path 137illustrates the flow of fluid. In FIG. 46, the exit orifice 138 andreentry orifice 139 are visible. FIG. 47 shows a membrane 140 when thevalve 136 is installed in a cassette. The membrane 140 may be set tocompress again the valve 136 and may be 0.032 inches thick. The membrane140 may use an UV-cured adhesive. The membrane 140 prevents the fluidfrom flowing in the wrong direction, e.g., opposite to that of the path137 as shown in FIG. 45. When the fluid attempts to flow in the wrongdirection, the suction force presses the membrane 140 against the exitorifice 138 preventing fluid from flowing from the reentry orifice 139to the exit orifice 138. Additionally or alternatively, a plungercoupled to an actuator may be used to compress the membrane 140 tofurther close the valve 136. In yet an additional embodiment of thepresent disclosure, a positive or negative pressure may be applied tothe top of the membrane 140 to control the valve 136.

FIG. 48 shows a sliding valve 141 having an inclined plane to providesealing in accordance with an embodiment of the present disclosure. Thesliding valve 141 includes a sealing surface 142 and a mounting surface143. As seen from FIG. 49 which shows a side view of the sliding valve141, the sliding valve 141 includes spring arches 144, and a wedge 145to create a downward force to seal the port 146 of the mount 147 asshown in FIG. 50.

A downward force on the spring arches 144 causes the sliding valve 141to slide away from the mounting surfaces 143 exposing the valve port146. When released, the spring arches 144 force the sealing arm 148towards the mounting surfaces 143, and the downward force wedges 145make contact with a molded counterpart in the mount 147 and force thesealing surface 142 onto the valve sealing surface port 146.

FIGS. 51-55 show a vent 149 for a reservoir 150 in accordance with anembodiment of the present disclosure. The vent 149 may be used on thefluid reservoirs 2, 3, or 4 in FIG. 1, may be used on the air filter 50or with the drain chamber 53 of the pump 19 as shown in FIG. 3. The ventincludes a septum 151, an air permeable filter 151, and a tube 153. Insome embodiments of the present disclosure, a reservoir 150 of aninfusate is rigid, e.g., a rigid IV bag or other fluid reservoir for afluid pumping device. The reservoir 150 may include a vent 149 to allowfluid flow out of a rigid reservoir 150 while venting the fluidreservoir 150 with an air permeable filter 152. In some embodiments, thevent 152 may not be impermeable to water vapor. However, by placing anoil plug 154 inline between the fluid reservoir 150 and the air filter152, infusate 155 losses are reduced because the oil 154 prevents theinfusate from evaporating through the oil plug 154.

The oil plug 154 is created by placing the septum 151 upstream of thereservoir 150 in a relatively narrow cross-sectioned section of thereservoir 150 as shown in FIGS. 51, 52, 53, 54, and 55. As shown in FIG.52, oil 154 is injected through the septum 151 through a filing needle156 before injecting the infusate 155 (as shown sequentially in FIGS. 53and 54). An amount of oil 154 is left in between the air filter 152 andthe infusate 155 at the end of the fill. As air is drawn into thereservoir 150 through the air filter 152, as shown in FIG. 55, the oil154 advances with the infusate 155 preventing evaporative losses.

Additionally or alternatively, in some embodiments, the oil plug 154 ispre-loaded into the tube 153 in between the septum 156 and the airfilter 152; for example, as would be the case if the fill procedurebegan as shown in FIG. 52.

FIGS. 56-58 illustrate the stages of a flow meter 157 in accordance withan embodiment of the present disclosure. FIG. 56 illustrates a firststage, FIG. 57 illustrates a second stage, and FIG. 58 illustrates athird stage. The stages of FIGS. 56-58 may be implemented as a method inaccordance with an embodiment of the present disclosure. A pumpdisclosed herein may be coupled upstream via the input port 162 and/oran infusion pump may be coupled to the output port 163 downstream tocreate a fluid from the input port 162 through the flow meter 157 to theoutput port 163.

The flow meter 157 includes a chamber 158 divided by a membrane 159. Themembrane 159 divides the chamber 158 into a first section 160 and asecond section 161. The flow meter 157 includes an input port 162 and anoutput port 163. The flow meter 157 includes first 164, second 167,third 166, and fourth 165 valves. The input port 162 is in fluidcommunication with the first section 160 via the first valve 164 and thesecond section 161 via the fourth valve 165. The output port 163 is influid communication with the first section 160 via the third valve 166and the second section 161 via the second valve 167. The chamber 158 maybe spherically shaped or cylindrically shaped. The chamber 158 may berigid, e.g., the chamber 158 may be made out of a plastic, metal, orother rigid or semi-rigid material.

The flow from the input port 162 to the output port 163 may be monitoredby use of the flexible membrane 159. The passage of fluid may becontrolled via actuation of the first valve 164, the second valve 167,the third valve 166, and the fourth valve 165. To fill the secondsection 161 of the chamber 158 and empty the first section 160 of thechamber 158, the first valve 164 and the second valve 167 are closedwhile the third valve 166 and the fourth valve 165 are opened. Thispushes the diaphragm or membrane 159 to the top side of the chamber 159as shown in FIG. 57. As illustrated in FIG. 58, this process can bereversed to fill the first section 160 and empty the second section 161by opening the first valve 164 and second valve 167 while closing thethird valve 166 and fourth valve 165. Because the volume of the chamber158 is known, the volume of fluid flowing through the input port 162 tothe output port 163 can be estimated by the movement of the membranebecause it is expected that the membrane 159 will become flush againstthe inner surface of the chamber 158.

To determine when the membrane 159 (i.e., diaphragm) has reached the topor bottom of the chamber 158, a pressure sensor could be added to theinput valve 162. When the membrane 159 reaches the end of the travel,the flow from the input port 162 will be occluded and the pressure willincrease. At this point, the valves can be switched (as shown in FIG.58) and the process continued on the opposite chamber.

In some embodiments of the present disclosure, the valves 164, 165, 166,and 167 may be mechanically toggled. The input port 162 pressure couldpotentially be used to mechanically toggle a switch that alternatelyopens and closes the two pair of valves in each state as illustrated byFIGS. 56-57, or FIG. 58. For example, the inlet pressure could expand aspring-loaded diaphragm which pushes on a latching mechanism thatcontrols the valves 164, 165, 166, and 167.

Additionally or alternately, in some embodiments, the chamber 158 may bemade of a clear material (polycarbonate, topaz, etc.) and the diaphragm159 out of an opaque material, and a camera may be used to observe thechamber 158 and detect when the diaphragm 159 has reached the end of itstravel. In yet another embodiment, a “target” image may be placed on thediaphragm 159 and a pair of stereo cameras (not shown) could detect whenthis target has reached the chamber 158 housing edge and is viewable.For example, there may be a camera to view the first section 160 fromthe outside and another camera to view the second section 161 from theoutside.

FIG. 59 shows a diagram of a disposable portion 168 of a flow rate meterin accordance with an embodiment of the present disclosure. Thedisposable portion 168 may be part of the flow meter 10, 11, or 12 ofFIG. 1, the flow meter 169 of FIG. 2 for use within the infusion sitemonitor 26, or may be the flow meter 48 of FIG. 3 for use with the pump19 (in some embodiments, the flow meter 48 is coupled to the tube 56).In yet additional embodiments, the disposable portion 168 is part of anintegrated flow rate meter and membrane pump. The disposable portion 168may interface with an upper clam-shell Acoustic Volume Sensing (AVS)assembly and a lower clam-shell AVS assembly (e.g., the upper clam-shellAVS assembly 192 and the lower clam-shell AVS assembly 193 of FIG. 70 asdescribed below). Acoustic volume sensing is described in greater depthin the section of the detailed description tilted “ACOUSTIC VOLUMESENSING”

The disposable portion 168 includes inlet tubing 170, an inlet occluderelease collar 171, an inlet Duck-bill occluding valve 172, a disposablebody 173, fluid tracks 174 and 181, an AVS chamber 175 (describedbelow), an air purge and spectral analysis window 176, and an outletassembly 177. The outlet assembly 177 includes an occluding valve 178, arelease collar 179, and an outlet tubing 180.

The duck-bill valves 172 and 178 may be actuated open by deforming theduck-bill (pinching the slot) when AVS clam-shells (see FIG. 70) areclosed over the AVS fluid chamber 175, and/or there may be separatecomponents on the tubing set to open the valves 172 and 178 manually(e.g. sliding an oval ring over the duck bill to open it, etc.).

The AVS chamber 175 may be utilized to measure the fluid flowing throughthe disposable portion 168. That is, the AVS system described below canmeasured the volume of fluid within the AVS chamber 175. The flow ratemay be communicated by a processor to the monitoring client 6, e.g., viaa wired or wireless connection. The measurement taken from the AVSchamber 175 may be operatively communicated to a processor, e.g., theprocessor 37 of the infusion site monitor 26 of FIG. 2 or the processor38 of the pump 19 of FIG. 3 to control the measurement of fluid flowingthrough the AVS chamber 175.

Referring to FIGS. 1 and 59, the disposable portion 168 may be used(with the full clam-shell AVS assembly described below) to control theflow of the pumps 19, 20, and/or 21 (directly or via a control systemwithin the monitoring client 6) or may be used to indicate when apredetermined amount of fluid has been fed into the patient 5, in whichcase a signal is sent to the pumps 19, 20, and/or 21 to stop fluid flow(directly or via a control system within the monitoring client 6). Insome embodiments, the disposable portion 168, when used as a flow meterwith the full clam-shell AVS assembly, can be used to run a pump in afixed volume mode with a variable fill and/or empty time, can be used torun in a variable volume with a fixed and/or variable fill or emptytime, or can be run in a fixed measurement interval, etc. Additionallyor alternatively, the disposable portion 168 may detect error conditionsor run-away conditions (e.g., fluid is flowing beyond a predeterminedthreshold), which may cause the flow rate meter using the disposableportion 168 to issue an alarm or alert, e.g., directly or to themonitoring client 6. The alarm or alert may be used to cause one or moreof the valves 16, 17, 18, and/or 25 to prevent additional fluid flow.

Referring again to FIG. 59, the disposable portion 168 may be formed bytwo or more sheets of barrier film or layers of barrier film and a rigidplastic sheet that are heat sealed together. The disposable portion 168may be used with (or is part of) the disposable portion 194 of FIGS.60-62, the disposable portion 201 of FIGS. 63-65, the disposable portion208 of FIGS. 66-68, and the disposable portion 220 of FIG. 69. The fluidtracks may be incorporated into the film and/or the rigid plastic (e.g.they may be thermally formed or simply an area of the film that is notheat sealed). For example, the rigid portion may define the fluid tracks174 and 181, and the AVS chamber 175; and a flexible layer may be placedover the rigid sheet such that the flexible layer is generally flat whenin an unpressured state over the rigid layer.

For example, the disposable portion 168 may be formed from three layersusing a rigid plastic sheet with a barrier film/membrane on either sidethat contains fluid tracks routed on one (or both) sides connected bythrough hole(s) in the rigid plastic sheet (e.g., a “via”).

The AVS chamber 175 may be incorporated into the film and/or the rigidplastic (e.g. thermally formed or simply an area of the film that is notheat sealed; that is, the chamber expands with the elastomeric potentialwhen filled). The fluid may be routed into the AVS chamber 175 via fluidtracks in the film/membrane, e.g., when using the three layer design.For example, the AVS chamber 175 may be fed by holes in the AVS chamber175 with the fluid tracks 174 and 181 on the opposite side. In someembodiments, these holes are part of a valving system that works on thefluid tracks on the opposite side. The tubes 170 and 180 may interfaceinto the fluid tracks 174. The tubes 170 and 180 include normally closedoccluding valves 172 and 178, respectively. Additionally oralternatively, in some embodiments of the present disclosure, theoccluding valves 172 and/or 178 may be one-way valves.

The air purge and spectral analysis window 176 may be transparent forspectral imaging and/or analysis of the composition of the fluidcontained therein. For example, the spectral analysis window 176 may beused by a camera to detect blood therein or to determine the spectralabsorption or reflection of the material therein which is compared to adatabase to determine the likely composition of the fluid and/or aconcentration of a material.

The air purge 176 may include a micorporous hydrophobic membrane thathas one side in contact with the infused fluid and the other side isexposed to atmosphere air. The micorporous hydrophobic membrane may belocated, in some specific embodiments, in a pressurized section of theflow path. The air purge and spectral analysis window 176 may include anintegral air bubble trap to prevent free flow of bubbles and/or pressuremay drives trapped bubbles across the membrane while fluid passes pastthe trap, etc.

The disposable portion 168 may optionally include several alignmentfeatures 182, which may be ink markers, holes, indentations, or otheralignment feature(s). The disposable portion 168 may be constructedusing stamping, vacuum forming and heat sealing, and can use materialsknown to be compatible with infusion fluids (e.g. IV bag materials,polycarbonates, Topaz, etc.).

FIGS. 60-62 show several views of a single-sided disposable portion 194of a flow meter in accordance with an embodiment of the presentdisclosure. FIG. 60 shows a side view of the disposable portion 194 of aflow meter, FIG. 61 shows a top view of the disposable portion 194 ofthe flow meter, and FIG. 62 shows an end view of the disposable portion194 of the flow meter.

The disposable portion 194 includes a one or more film layers 195 thatdefine a fluid space 196 with a bottom film 197 that may be rigid (insome embodiments the bottom film 197 is semi-rigid or flexible). As iseasily seen in FIG. 61, the film 195 also forms an AVS chamber 198. Asseen in FIG. 62, the AVS chamber 198 is positioned to measure the fluidflowing into and out of the AVS chamber 198 via the fluid track 199. Thefluid track 199 interfaces with the AVS chamber 198 allowing it toexpand as fluid enters into the AVS chamber 198 from the fluid track199. The fluid track 199 may hold a volume of, in some specificembodiments, 0.025 cc allowing for 300 milliliters per hour maximum flowrate. The layers 195 are head bonded along length 200.

As shown in FIG. 62, the fluid track 199 formed by the layer 195 isvisible and the AVS chamber 198 is also visible; however, the layer 195,in some embodiments, transitions from the fluid track 199 to the AVSchamber 199 when transitioning from the left side of the disposableportion 194 to the right side as shown in FIG. 61. For example, in FIG.62, the fluid track layer 199 is relatively proximal (along a length 284of FIG. 61) to the AVS chamber 198 (which is along a length 285 of FIG.62), which is distal in the view shown in FIG. 62.

FIGS. 63-65 show several views of a double-sided disposable portion 201of a flow meter in accordance with an embodiment of the presentdisclosure. The disposable portion 201 includes one or more top films202 with one or more bottom films 203 that together define a fluid space204. Either one of the films 202 and/or 203 may be rigid, semi-rigid,flexible, or elastic. In additional specific embodiments, a rigid,planar layer may be positioned between the layers 202 and 203 (notdepicted) with the layers 202 and 203 being flexible.

As is easily seen in FIG. 64, the films 202 and 203 form an AVS chamber205. As is easily seen FIG. 65, the AVS chamber 205 can measure fluidreceived from a fluid track 206. Also, fluid may leave the AVS chamber205 via the fluid track 206. As also shown in FIG. 65, the heat sealedand/or bonded interface 207 is shown. As mentioned, in some embodiments,a rigid member (not shown) may be placed in the center of the layers 202and 203 thereby defining two AVS chambers 205 and two fluid tracks 206;in this specific embodiment, a small hole may exists between the twofluid tracks 206 and/or the two AVS chambers 206 to provide pressureequalization therebetween. Any common mode compliance of the fluid track206 would be accounted for by one of the AVS chambers 205 therebyproviding a self balancing of the AVS measurements.

FIGS. 66-68 show several views of a three-layer, opposite-sided,disposable portion 208 of a flow meter in accordance with an embodimentof the present disclosure. The disposable portion 208 is formed by a toplayer 209 and a bottom layer 212 having a rigid plastic layer 210therebetween. The rigid plastic layer 210 has two holes 217 and 218 thatallow fluid to pass between a fluid space 211 and the AVS chamber 213.

The fluid passes from the fluid track 215 through the holes 217 and 218to transgress through the AVS chamber 213. Also, the disposable portion208 includes a heat bonded portion 219.

FIG. 69 shows a top view of another disposable portion 220 of a flowmeter in accordance with another embodiment of the present disclosure.The disposable portion 220 includes one or more layers bonded to a rigidbody 259. The rigid body 259 includes a cut-out portion 260. The AVSchamber 261 may protrude out of both side of the rigid body 259 allowingan AVS assembly (not shown) to surrounding the AVS chamber 261 toestimate the volume of the AVS chamber 261. Air may completelytransgress through the cut-out portion 260 such that a variable volumemay be positioned completely (or substantially) around the AVS chamber261. The disposable portion 220 may be formed from one or more elasticlayers sealed to the rigid body 259. The disposable portion 220 includesfluid tracks 262 and 263 enabling fluid to transgress and egress throughthe AVS chamber 261.

FIG. 70 shows a flow meter 221 including a full AVS clam shell assemblyand a single-sided disposable portion (e.g., the disposable portion 194of FIG. 62) in accordance with an embodiment of the present disclosure.The flow meter 221 may fill 0.025 cc of liquid for up to 300 millilitersper hour.

The AVS clam shell assembly includes the upper clam-shell AVS assembly192 and the lower clam-shell AVS assembly 193. The lower clam-shell AVSassembly 192 may be slightly biased for proper seating in the lowerbacking 233 and/or it may include a rigid plastic sheet or stiffener tocompliment the vents 224. The upper and lower clam-shell AVS assemblies192 and 193 may circumferentially surround the AVS fluid volume 224,e.g., just outside the heat seal using a trough/protrusion “pinch”; andan o-ring may optionally also be used to seal the AVS fluid volume 224.The flow meter 221 may optionally include an air sensor as describedherein, e.g., ultrasonic- and/or camera-based air sensor, to determineif air beyond a threshold is being delivered to a patient; an alarm oralert may be issued in response to the air exceeding the threshold.Additionally or alternatively, the air may be subtracted from the volumeof liquid estimated as flowing through the flow meter 221.

The flow meter 221 includes an AVS reference chamber 222, a referencemicrophone 223, a resonance port 224, an integral perimeter seal orvalve 225 (shown in the open state), another integral perimeter seal orvalve 230 (shown in the sealed state), a variable volume microphone 226,a speaker 227, and a variable volume 228. The flow meter 221 alsoincludes a spring disk 229. The spring disk 229 may include a small holefor pressure equalization. The spring disk 229 may be formed, in someembodiments, out of an elastomeric film or layer. In some embodiments,the spring disk 229 is used to bring in fluid into the AVS fluid volume224. The spring disk 229 may provide a spring via pre-forming and/or thevariable volume 228 may have a negative or positive pressure relative toeither the ambient air and/or the fluid flowing through the AVS fluidvolume 224.

The valves 225 and 230 slide along the body of the upper clam-shell AVSassembly 192 to permit or occlude fluid from enter or leaving the AVSfluid volume 224. The valves 225 and 230 are coupled to an actuator(e.g., linear servo, linear stepper motor, a cam follower coupled to arotating cam, etc.) to control the valve states of the valves 225 and230. The valves 225 and/or 230 may: be normally closed; actuated open(e.g., using a solenoid and/or Nitinol); include a position sensor;cone-shaped (e.g., a cone shaped plunger from the fluid track sidepushes through the elastomer into the AVS chamber inlet/outlet holes toform a seal); and may include an opposing pressure seal to determine ifthe valve is applying sufficient pressure. The actuators may be coupledto a processor disclosed herein (e.g., the processor 37 of FIG. 2 or 3).The valves 225 and/or 230 may both close in an error condition toprevent fluid from being sent to a patient, e.g., when the processor 37of FIG. 2 or 3 and/or the monitoring client 6 determines that an errorcondition exists that requires the stoppage of the fluid flow to thepatient. The processor may coordinate operation of the valve 225 and 230such that the AVS volume 226 is filled when, for example, a pulsing pumppumps liquid downstream. The flow rate meter 221 may coordinate itsoperation with a pump, e.g., via wireless information received from thepump, such as a flow rate, pulse times, pulse durations, pulse volumes,pulse frequency, etc.

The speaker 227 emits one or more acoustic frequencies which arereceived by the reference microphone 223 and the variable volumemicrophone 226. The acoustic gain between the microphones 223 and 226may be correlated with the volume of the variable volume 228 todetermine the volume through the flow rate meter 221. Additionally oralternatively, the phase shift between the microphones 223 and 226 maybe correlated with the volume of the variable volume 228. The speaker227 and the microphones 223 and 226 may be in operative communicationwith one or more processors to implement an algorithm to determine thevolume using AVS, e.g., the processor 37 of FIG. 2 or 3. Additionaldetails related to the operation of AVS are described infra in thesection entitled “ACOUSTIC VOLUME SENSING.”

The films 231 and 233 define a fluid space 232. As the fluid varieswithin the AVS fluid volume 224 by entering and leaving via the fluidspace 232, the difference in volume is calculated to determine the flowrate via the flow meter 221. That is, the variable volume 228 has anacoustic response that may be used to determine the AVS fluid volume224. The flow meter 221 also includes ventilation paths 225 to preventair from building up under the film 233 that defines the AVS fluidvolume 224.

In yet an additional embodiment of the present disclosure, the flow ratemeter 221 may be utilized as part of a membrane pump. For example, anactuator (not shown) may interface with the spring disk 229 (or the film231) to providing a pumping action with the AVS fluid volume 224; theactuator may exists within the variable volume or may interface with thespring disk 229 via a shaft that transgresses through the upper clamshell assembly 192 (with an appropriate acoustic seal). The shaft'svolume may be accounted for in the AVS measurement and/or the entireactuator may be in the variable volume.

FIG. 71 shows a side view of a flow rate meter 234 including a top AVSassembly 236 and bottom AVS assembly 238 with integral perimeter sealvalves 239 and 340 in accordance with an embodiment of the presentdisclosure. The flow rate meter 234 may include the disposable portion201 of FIGS. 63-65. The flow rate meter 234 may allow for flows of up to0.25 cc per fill for up to 300 milliliters per hour, in some specificembodiments, e.g., 0.125 cc for each side for 150 millimeters per houron each side.

The top AVS assembly 236 measures the acoustic response of the topvariable volume 241 and the bottom AVS assembly 238 measures theacoustic response of the bottom variable volume 242. The measurements ofthe acoustic response of the top and bottom variable volumes 241 and 242may be correlated to the top and bottom variable volumes 241 and 242.The volume of the AVS fluid chamber 243 may be estimated by subtractinga predetermined total volume from the volumes of the AVS chambers 241and 242. A processor disclosed herein (e.g., processor 37 of FIG. 2 or3) may estimate the volume of the AVS fluid chamber 243.

In yet an additional embodiment of the present disclosure, the flow ratemeter 234 may be utilized as part of a membrane pump. For example, oneor more actuator (not shown) may interface with the spring disks 235and/or 237 (or the AVS fluid chamber 243) to provide a pumping actionwith the AVS fluid volume 243; the actuator may exists within thevariable volumes 243 and/or 242 or may interface with the spring disks235 and/or 237 via a shaft that transgresses through the AVS assemblies236 and/or 238 (with an appropriate acoustic seal). The shaft's volumemay be accounted for in the AVS measurement and/or the entire actuatormay be in the variable volume.

FIG. 72 shows a side view of another flow rate meter 244 including asingle-sided AVS assembly 245 with surrounding variable volumes 246 and247 in accordance with another embodiment of the present disclosure. Theflow rate meter 244 may use the disposable portion 220 of FIG. 69. Thevariable volumes 246 and 247 may be in fluid communication with eachother around the edges of the AVS fluid chamber 248. The AVS assembly245 measures the acoustic response of the chambers 246 and 247 tocorrelate the volume of the AVS chambers 246 and 247. The total volumeof the AVS chambers 246 and 247 is subtracted from the predeterminedtotal volume to estimate the volume of the fluid within the AVS fluidvolume 248.

In yet an additional embodiment of the present disclosure, the flow ratemeter 244 may be utilized as part of a membrane pump. For example, oneor more actuators (not shown) may interface with the spring disks 286and/or 287 (or the AVS fluid chamber 248) to provide a pumping actionwith the AVS fluid volume 248; the actuator may exist within thevariable volumes 246 and/or 247 or may interface with the spring disks286 and/or 287 via a shaft that traverses through the AVS assembly 245(with an appropriate acoustic seal). The shaft's volume may be accountedfor in the AVS measurement and/or the entire actuator may be in thevariable volume.

FIG. 73 shows a side view of yet another flow rate meter 249 includingtwo piston valves 250 and 251 in accordance with another embodiment ofthe present disclosure. The piston valves 250 and 251 may be coupled toactuators which are, in turn, coupled to a processor, e.g., theprocessor 37 of FIG. 2 or 3. The flow rate meter 249 includes a top AVSclam-shell assembly 252 and a bottom AVS claim-shell assembly 253. Thefluid flows from the fluid track 254, through a hole 255 and into theAVS fluid chamber 256. Thereafter, the fluid can flow through the hole257 (when the valve 251 is in the open state, through the fluid track258) and finally out of the flow rate meter 249. The piston valves 250and/or 251 may alternatively open and close such one of the pistonvalves is open while the other one is closed. The spring disk 229 mayassist in the intake of the fluid or the expelling of the fluid out ofthe AVS fluid chamber 256.

In yet an additional embodiment of the present disclosure, the flow ratemeter 249 may be utilized as part of a membrane pump. For example, oneor more actuators (not shown) may interface with the spring disk 288 (orthe AVS fluid chamber 257) to provide a pumping action with the AVSfluid volume 257; the actuator may exist within the variable volume 289or may interface with the spring disk 289 via a shaft that transgressesthrough the AVS assembly 252 (with an appropriate acoustic seal). Theshaft's volume may be accounted for in the AVS measurement and/or theentire actuator may be in the variable volume.

FIG. 74 shows a flow rate meter 259 having top and bottom AVS assemblies(262 and 263, respectively) which provide a semi-continuous flow inaccordance with an embodiment of the present disclosure. The flow ratemeter 259 includes valves 260, 261, 264, and 265. The valves 260, 261,264, and 265 may operate together to fill an AVS fluid volume 266 and267 in a sequential, but opposite, manner. For example, the valves 260,261, 264, and 265 may operate to fill the AVS fluid volume 266 whiledischarging the other AVS fluid volume 267, and vice versa. That is,when an AVS fluid volume is being filled, the other AVS fluid volume mayhave an AVS measurement taken by the respective AVS assembly.

The flow rate meter 259 also includes a small reservoir 268 to buffer tofluid flowing from a pump and a variable occluder 269 that may becoupled to a processor. The variable occluder 269 may be varied suchthat the discharge of the AVS fluid volumes 266 and 267 are “smoothed”out to produce a semi-continuous flow to the patient (e.g., the AVSfluid volumes 266 and 267 may be spring loaded, such as with a diskspring, to force out the fluid). The processor may use the feedback fromthe AVS assemblies 262 and 263 to adjust the variable occlude 269 toachieve a target flow rate to a patient.

In one specific embodiment, the flow rate meter 259: measures flow overa range of 0.1 to 300 ml/hr; allows for non-metered flow rates ofgreater than 300 ml/hr to 2000 ml/hr; the flow resistance does notexceed 1 PSI across a flow range of 0.1 to 2000 ml/hr; the active volumeaccumulation does not exceed 2 millimeters; has a hold up volume of lessthan 0.5 ml; has a size of less than 1 inch, by 3 inches, by 1 inch forthe disposable; may be battery or wired powered and may run at a rate of100 ml/hr for κ hours on the battery power; and may include a userinterface that communicates with all of the valves, sensors, andcomponent wirelessly.

FIG. 75 shows a flow rate meter 276 having two in-line AVS assemblies270 and 271 with several valves 272, 273, 274, 275, and 277 to controlto fluid flowing therethrough in accordance with an embodiment of thepresent disclosure. The valve 275 allows the least amount of fluid flowinto the AVS volume 279 from the AVS volume 278, the valve 274 allowsmore fluid to flow into the AVS volume 279 from the AVS volume 278, andthe valve 273 allow the most amount of fluid to flow into the AVS volume279 from the AVS volume 278. The valves 273, 274, and 275 may becontrolled to control the flow from the pump to the patient.

The two AVS assemblies 270 and 271 may each take measurements of the AVSfluid volumes 278 and 279, respectively. The AVS fluid volumes 278 and279 may be different because of a pressure differences caused by thevalves 273, 274, and 275 as the fluid flow from the pump to the patient.The continuous fluid flow causes a difference in pressure based upon theBernoulli principle.

A continuous flow sensor may utilize the Bernoulli principle. Forexample, a fixed orifice or other restriction in a flow path of a fluid(e.g., one caused by an orifice plate) may be used to measure a pressuredrop across the orifice to determine the flow rate based on theBernoulli principle illustrated in Equation (33) as follows:

$\begin{matrix}{Q = {C_{d}\sqrt{\frac{2\Delta \; p}{\rho}}{\frac{A_{2}}{\sqrt{1 - \left( \frac{A_{2}}{A_{1}} \right)^{2}}}.}}} & (33)\end{matrix}$

Where Q is the volumetric flow rate, C_(d) is the discharge coefficientwhich relates to turbulence of flow, ρ is the density of the fluid, A₁is the cross-sectional area just in front of the restriction, A₂ is thecross-sectional area of the restriction, and Δp is the pressure dropacross the restriction. Equation (33) may be simplified to Equation (34)as follows:

$\begin{matrix}{Q = {C_{f}A_{0}{\sqrt{\frac{2\Delta \; p}{\rho}}.}}} & (34)\end{matrix}$

Ao is the area of the orifice, and C_(f) is a constant related to theturbulence and flow geometry specific to the restrictor design (C_(f)typically has a value between 0.6 and 0.9 that is derived empirically).Therefore, the estimated flow rate is related to the area of the orificeand the square root of the measured pressure drop. The estimated flowrate is also related to the density of the fluid being measured and theorifice geometry.

Therefore, the valves 273, 274, and 275 of the flow meter 276 may beconsidered a restrictor (e.g., serving as an orifice plate in acontinuous flow rate meter) to produce a measurable pressure differencebetween the AVS volumes 278 and 279. The AVS volumes 278 and 279 may becorrelated with respective pressures because the respective membranesforming the AVS chambers 278 and 279 will stretch based upon thepressure therein.

For example, the valves 272 and 277 may be opened thereby allowing fluidto continuously flow from the pump to the patient. The AVS volumes 278and 279 will have a difference in pressure caused by the totalrestriction from one or more of the valves 273, 274, and 275 (which may,in some embodiments, be modeled as an orifice).

The differential AVS volume measurements between the AVS chambers 278and 279 are proportional to flow rate (the pressure difference may becorrelated with flow rate empirically). Any common-mode, down-streampressure change would result in a volume increase in both of the AVSchambers 278 and 279 thereby subtracting out the increase in the AVSchambers 278 and 279. Additionally, a predetermined positive change inthe AVS volume measurements may be considered an indication of anocclusion, and a predetermined change in the flow rate may trigger analarm and/or alert.

The valves 273, 274, and 275 allow a range of flow rates from the pumpto the patient to be used and also change the measurement range of theflow rate meter 276. A processor can actuate one or more valves 273,274, and 275 and can determine the total restriction of occlusion causedby the valves 273, 274, and 275. That is, the configuration of thevalves 273, 274, and 275 may be correlated with a model, e.g., across-sectional area of a restriction using Equation (33) or (34), fordetermining the flow rate. The processor may vary the valves 273, 274,and 275 to determine the flow rate within a desired measurement flowrate range.

The AVS assemblies 270 and 271 perform a measurement within apredetermined amount of time by sweeping acoustic frequencies (asdescribed herein), e.g., for one-half a second or 1/20 of a second. Insome embodiments, the AVS assemblies 270 and 271 may perform two typesof frequency sweeps, e.g., a shorter frequency sweep (e.g., performed inless time) and/or a full frequency sweep, e.g., to do other errorchecking such as, for example, to check for acoustic leak(s). The flowrate meter 276 may, in some embodiments, coordinate with a pump tointroduce a periodic disturbance to calibrate the flow meter 276 and/orfor error checking. Additionally or alternatively, small reservoirs 400and 401 may provide fluid dampening to “smooth” the flow in someembodiments. The fluid reservoirs 400 and 401 may be formed from anelastic material that defines a bubble-type flexible bladder.

The valves 272 and 277 may have their operation coordinated to check forerror conditions. For example, the valve 272 may be closed while thevalve 277 remains open to determine if the fluid is being discharged tothe patient for error checking (e.g., to check for occlusions, etc.).

In some embodiments, the valves 272, 273, 274, 275, and 277 are used sothat the AVS volumes 278 and 279 are operated such that one of the AVSvolumes is filled with a liquid while the other AVS volume is dischargesthe liquid thereby providing a piece-wise continuous flow measurementsusing the AVS volumes 278 and 270. Additionally or alternatively, thevalves 272, 273, 274, 275, and 277 may also be used to do a “flow tozero” test to do a “flow zero” correction (e.g. correct for volume driftof the AVS volume measurements).

In one specific embodiment, the flow rate meter 276: may measurecontinuous flow over a range of 0.1 to 300 ml/hr (in some embodiments upto 2000 ml/hr); has an accuracy of measurement of +/−0.02 ml/hr from 0.1to 2.5 ml/hr, or 5% otherwise; measures fast enough to be insensitive toflow disturbances of a 10% change in flow in 1 second; measures withhead height pressure changes of +/−2 PSI; does not add flow resistanceexceeding 1 PSI across a flow range of 0.1 to 2000 ml/hr; has a size ofless than 1 inch, by 3 inches, by 1 inch for the disposable; may bebattery or wired powered and may run at a rate of 100 ml/hr for 8 hourson battery power; and may include a user interface that communicateswith all of the valves, sensors, and components wirelessly.

FIG. 76 shows a membrane pump 280 having a negative pressure source 281in accordance with an embodiment of the present disclosure. The membranepump 280 includes valves 282 and 283 that can alternate between applyinga negative pressure to the variable volume 290 and apply atmosphericpressure to the variable volume 290. The valves 282 and 283 are fluidlyconnected to the AVS reference volume 402 via a port 403 that is of asufficiently small size that does not introduce acoustic artifacts,e.g., 0.020 inches in some specific embodiments. A processor, e.g.,processor 37 of FIG. 3, may control the valves 282 and/or 283 to achievea target pressure within the reference volume 402 as measured by apressure sensor 404. The processor, e.g., processor 37 of FIG. 37 ofFIG. 3, may be in operative communication with the valves 282 and 283,and with the pressure sensor 404.

The valve 282 may be closed and the valve 283 may be opened therebyputting the variable volume 290 in fluid communication with the negativepressure source 281. Thereafter, the valve 283 may be closed and thevalves 282 opened to put the variable volume 2190 in fluid communicationwith atmospheric air. This may be continually repeated to repeatedlyoscillate the pressure within the variable volume 290. In some specificembodiments AVS measurements are made when the variable volume 402 isplaced in a static pressure state (e.g., set to ambient pressure, thestatic negative pressure, or by closing the valves 282 and 283), and theAVS fluid volume 293 is placed in a static pressure state (e.g., thepiston valves 291 and 292 are closed).

As previously mentioned, a negative source 281 may be applied to thevariable volume 290 by opening the valve 283 and closing the valve 282.When the negative pressure is applied to the variable volume 290, thepiston valve 291 may be opened and the piston valve 292 closed to drawfluid into the AVS fluid volume 293. Thereafter, the valve 283 and thepiston valve 291 are closed so that an AVS measurement may be taken bythe AVS assembly 249 (the AVS assembly 294 includes a lower AVSclam-shell assembly 296). Optionally, the piston valves 291 and 292 maybe closed prior to or during the AVS measurement. Thereafter, the valve282 and the piston valve 292 are opened to allow fluid to flow into thefluid channel 295 from the AVS chamber 293. Next, the piston valve 292and the valve 282 are closed, and another AVS measurement is taken fromthe AVS chamber 293. The difference in these AVS measurements may becorrelated to the amount of fluid pumped for each respective pumpingcycle. That is, each pulse of liquid to the patient may be estimated bysubtracting one AVS measurement from another AVS measurement. In somespecific embodiments the AVS measurements are each taken at the samepressures of the AVS volume 290 (e.g., at atmospheric pressure or astatic negative pressure, as may be determined by the pressure sensor404) to account for the effects of positive and negative pressures onair-bubble volume thereby mitigating the effect that an air bubble hason the fluid volume flow measurements.

FIG. 77 shows a membrane pump 300 having a negative-pressure source 296and a positive-pressure source 297 coupled to valves 298 and 299,respectively, in accordance with an embodiment of the presentdisclosure. The negative-pressure source 296 may be in fluidcommunication with the variable volume 301 when drawing fluid into theAVS chamber 302. Likewise, the positive-pressure source 297 may be influid communication with the variable volume 301 when discharging fluidout of the AVS chamber 302. The variable volume may be coupled toatmospheric pressure 303 via a valve 304 when an AVS measurement istaken.

Note that no disk spring is used in the embodiment shown in FIG. 77. TheAVS fluid volume 302 is formed by a flaccid material that generateslittle or no pressure within the variable volume 301. In someembodiments of the present disclosure, the pump 300 takes AVSmeasurements all at the same pressure to account for the pressureeffects on bubble size; for example: the AVS volume measurement may betaken as follows: (1) close the piston valve 405, open the piston valve406, open the valve 298, close the valve 299, and close the valve 304thereby causing fluid to be drawn into the AVS chamber 302 with thenegative pressure from the negative-pressure source 296; (2) close thepiston valve 406 and close the valve 298; (3) open the valve 304 therebycausing the pressure of the variable volume 301 to reach atmosphericpressure 303; (4) close the valve 304; (5) take an AVS measurement; (6),open the valve 299 and open the piston valve 405 thereby discharging thefluid out of the AVS volume 302; (7) close the piston valve 405 andclose the valve 299; (8) open the valve 304 to equalize the variablevolume pressure to atmosphere 303; (9) close the valve 304; (10) take anAVS measurement; (11) and compare the AVS volumes measurements todetermine the volume discharged, e.g., to estimate flow rate. Theprevious example may be modified to take one or more AVS measurements inpositive pressure, negative pressure, atmospheric pressure, or in somecombination thereof.

In yet an additional embodiment, the positive pressure source 297 isused to take AVS measurements when the variable volume 301 is under apositive pressure. For example, in some embodiments of the presentdisclosure, the pump 300 takes AVS measurements all at a positivepressure to account for the pressure effects on bubble size; forexample: the AVS volume measurement may be taken as follows: (1) closethe piston valve 405, open the piston valve 406, open the valve 298,close the valve 299, and close the valve 304 thereby causing fluid to bedrawn into the AVS chamber 302 with the negative pressure from thenegative-pressure source 296; (2) close the piston valve 406 and closethe valve 298; (3) open the valve 299 thereby causing the pressure ofthe variable volume 301 to reach a predetermined positive pressure asindicated by the pressure sensor 407; (4) close the valve 299; (5) takean AVS measurement; (6) open the valve 304 and open the piston valve 405thereby discharging the fluid out of the AVS volume 302; (7) close thepiston valve 405 and close the valve 304; (8) open the valve 299 therebycausing the pressure of the variable volume 301 to reach a predeterminedpositive pressure as indicated by the pressure sensor 407; (9) close thevalve 299; (10) take an AVS measurement; (11) and compare the AVSvolumes measurements to determine the volume discharged, e.g., toestimate flow rate. The previous example may be modified to take one ormore AVS measurements in positive pressure, negative pressure,atmospheric pressure, or some combination thereof.

The pump 300 may also, in some embodiments, determine if there iscompliance in the system, such as compliance caused by air, by takingAVS volume measurements at two different pressures. For example, two AVSmeasurements may be taken during the fill phase at two differentpressures (e.g., negative pressure and ambient pressure, or some othercombination) and/or during the discharge phase at two differencepressures (e.g., negative pressure and ambient pressure, or some othercombination). The change in volume at the two pressures may becorrelated with compliance of the AVS volume 302, such as if there wasan air bubble in the fluid. If a predetermined amount of AVS volume 302variation is determined to exists, a processor may determine an errorcondition exists and issue an alarm or alert. In yet another embodiment,the flow rate measurement may be corrected for the air volumemeasurement taken; For example, a processor may determine the volume ofair that was delivered to the patient instead of a drug, such asinsulin, and compensate the delivery of the insulin to ensure that theprescribed does of insulin is delivered. For example, consider thefollowing additional embodiments.

In some embodiments of the present disclosure, compliance may beestimated in the pump 300 by taking at least two AVS measurements atdifferent pressures to account for air bubbles; for example: the AVSvolume measurements may be taken as follows: (1) close the piston valve405, open the piston valve 406, open the valve 298, close the valve 299,and close the valve 304 thereby causing fluid to be drawn into the AVSchamber 302 with the negative pressure from the negative-pressure source296; (2) close the piston valve 406 and close the valve 298; (3) take anAVS measurement while the reference volume 301 remains under negativepressure; (3) open the valve 304 thereby causing the pressure of thevariable volume 301 to reach atmospheric pressure 303; (4) close thevalve 304; (5) take an AVS measurement while the reference volume 301remains at atmospheric pressure; (6) compare the two AVS measurementsfrom (3) and (5) to determine compliance of the AVS volume 302; (7) openthe valve 299 and open the piston valve 405 thereby discharging thefluid out of the AVS volume 302; (8) close the piston valve 405 andclose the valve 299; (9) take an AVS measurement while the variablevolume 301 remains under positive pressure; (10) open the valve 304 toequalize the variable volume pressure to atmosphere 303; (11) close thevalve 304; (12) take an AVS measurement while the variable volume 302remains under atmospheric pressure; (13) compare the two AVSmeasurements from (9) and (12) to determine compliance of the AVS volume302; (14) and compare at least two AVS volume measurements to determinethe volume discharged, e.g., to estimate flow rate. The above examplemay be modified in various ways such that the two AVS measurementshaving two different pressures and may occur during the filling stage,the discharging stage, any other stage of the pumping, using one or moreof a positive pressure measurement, a negative pressure measurement, anatmospheric pressure measurement, or some combination thereof.

Consider yet another embodiment: the AVS volume measurement and pumpingaction may occur as follows: (1) close the piston valve 405, open thepiston valve 406, open the valve 298, close the valve 299, and close thevalve 304 thereby causing fluid to be drawn into the AVS chamber 302with the negative pressure from the negative-pressure source 296; (2)close the piston valve 406 and close the valve 299; (3) take an AVSmeasurement when the variable volume 301 remains at a negative pressure;(4) open the valve 299 thereby causing the pressure of the variablevolume 301 to reach a predetermined positive pressure as indicated bythe pressure sensor 407; (5) close the valve 299; (6) take an AVSmeasurement when the variable volume 301 is at a positive pressure; (7)compare the two AVS measurement from (3) and (6) to determine complianceof the AVS volume 302; (8) open the valve 304 and open the piston valve405 thereby discharging the fluid out of the AVS volume 302; (9) closethe piston valve 405 and close the valve 304; (10) take an AVSmeasurement while the variable volume 301 is at an atmospheric pressure(in another embodiment, the AVS volume measurement is taken at anegative pressure); (11) open the valve 299 thereby causing the pressureof the variable volume 301 to reach a predetermined positive pressure asindicated by the pressure sensor 407; (12) close the valve 299; (13)take an AVS measurement; (14) and compare at two AVS volume measurementsto determine the volume discharged and/or the compliance of the variablevolume, e.g., to estimate flow rate. The above example may be modifiedin various ways such that the two AVS measurements having two differentpressures may occur during the filling stage, the discharging stage, anyother stage of the pumping, using one or more of a positive pressuremeasurement, a negative pressure measurement, an atmospheric pressuremeasurement, or some combination thereof.

In one specific embodiment, the membrane pump 300: has a flow ratetarget of 0.1 to 2000 ml/hr; can generate at least a maximum of 3 PSIand up to 10 PSI; can draw fluid from a reservoir of a maximum ofnegative pressure of at least −2 PSI; may be battery powered; may bepowered by a cable; and may have a user interface that wirelesslycommunicates with a processor coupled to all actuators, valves, pressuresensors, and other devices.

FIG. 78 shows an optical-sensor based flow rate meter 305 in accordancewith an embodiment of the present disclosure. The flow rate meter 305includes an IR source 306 that reflects light off a flexible membrane307. The reflected IR light is received by a sensor 308. The sensorformed by the IR source 306 and the IR sensor 308 may be a sensor withthe part number: GP2S60 manufactured by Sharp Corporation. The lightreflected off of the membrane 307 may be correlated to a volume 309.With an upstream or downstream pump (not shown) used in conjunction withinput and outlet valves (not shown) the flow rate me be calculated bymeasuring the light as it reflects off the membrane 307. Since a changein fluid pressure in the line results in a displacement of the elastomermembrane 309, the distance between the sensor 308 varies as a functionof the pressure in the fluid line; therefore the output of the sensor isproportional to the pressure in the fluid line and may be correlatedwith pressure and/or volume.

The flow rate meter 305 may be used by a membrane pump disclosed hereinto facilitate positive and/or negative pressure measurements. Thepressure sensitivity may be tuned by selecting the elastomericproperties of the membrane and the area of fluid contact with themembrane forming the AVS volume 309. The reflective property of theelastomeric membrane may be enhanced with metal, plastic, film, or otherreflective material. A temperature sensor may be added to account forthe thermal effects of the material that forms the AVS volume 309. Aheat sink and/or thermal controller around the elastomer AVS chamber 309may be used to mitigate thermal effects, in some specific embodiments.

The IR source 306 may be pulsed and/or multiplexing may be used withmultiple IR sources 306 and multiple sensors 307 to inhibit cross-talkerror. An initial reading may be used as an offset null, and the changein sensor output may be correlated with changes in pressure in the AVSvolume 308. Focusing optics may be used with the disposable portion,e.g., the membranes, to facilitate the ranging and aligning of the IRsource 306 and the IR sensor 308. In alternative embodiments, anultrasonic proximity sensor is used instead of the IR source 306 and theIR sensor 308.

In one specific embodiment, the flow rate meter 305 may: have asensitivity to line pressure over a range of −2 to +10 PSI; may measurea line pressure to within +/−20% over a range of 1 to 10 PSI; have aresolution of at least 10 bits; and may be low power.

FIG. 79 shows a pressure-controlled membrane pump 322 in accordance withan embodiment of the present disclosure. FIGS. 80-82 show a legend forreference herein; that is, refer to FIG. 80-82 for the legend of symbolsfor FIGS. 83, 85, 87, 88, 90, 91, 93, 95, and 97. Referring again toFIG. 79, the membrane pump 322 includes an AVS assembly 323 having areference volume 324 and a variable volume 325. The reference volume 324includes a speaker 326 for generating an acoustic signal in thereference chamber 324 which travels through a port 357 to the variablevolume 325. The acoustic signal is received by a reference microphone327 and a variable-volume microphone 328. The signals from themicrophones 327 and 328 are compared to determine an acoustic responseto measure the volume of the AVS chamber 335. An optional optical sensor329 may be used to reflect light off of a membrane forming the AVSchamber 335. The optical sensor 329 may be used to facilitate theestimation of the volume of the AVS chamber 335. In some embodimentsmultiple optical sensors 329 may be used.

The pump 353 may be a diaphragm pump, such as one having the partnumber: T3CP-1HE-06-1SNB, manufactured by Parker Hannifin Corporationlocated at 6035 Parkland Boulevard, Cleveland, Ohio 44124-4141;additionally or alternatively, other pump types and/or pumpsmanufactured by any other manufacturer may be utilized.

A variable voltage applied to the pump 353 (see FIG. 79) may be adjustedin real time to reach a desired pressure as measured by the pressuresensor 340. The pump 353 can have a flow rate of several liters perminute. The variable volume 325 may have an air volume of 0.5 cc, andmay be pressure limited to between 1-10 PSI. In some embodiments, thepump 353 has a fill and empty cycle time of 1 Hz and a fluid chamber of0.5 cc resulting in a max flow rate of 1800 cc/hr, for example. Inadditional embodiments, variable pressure may be controlled in burststhat last in the tens of milliseconds and six aliquots may be deliveredover an hour interval to achieve a flow rate of 0.1 cc/hr. In additionalembodiments, an alternative pneumatic flow path (not shown) having apneumatic flow restriction may be used to lower the working pressure onthe variable volume 324 thereby facilitating low and high volumetricflow ranges.

A fluid reservoir 331 is coupled through a fluid path to a one-way valve332. The valve 332 may be a pinch valve. An optical sensor 333 measureswhen the valve is closed, e.g., an optical beam may be broken when thepinch valve 332 is open or the optical beam is broken when the pinchvalve 332 is closed.

The fluid travels into the AVS volume 335 through a fluid line 334. Thefluid may be discharged through a fluid path to a one-way valve 336 thatis also measured using an optical sensor 337. Finally, the fluid entersinto a patient 338.

The reference chamber 324 and the variable volume chamber 325 are influid communication with a line 339. A pressure sensor 340 measures thepressure of the line and hence the chambers 324 and 325. Additionally oralternatively, the pump 322 includes a temperature sensor 330. Thepressure from the pressure sensor 340 and/or the temperature from thetemperature sensor 330 may be used for to increase the accuracy of AVSmeasurements.

The valve 341 connects the tube 339 to the ambient pressure 342. Apressure sensor 343 measures ambient pressure. The valve 341 is alsocoupled to a valve 344 which, in turn, is connected to a negativepressure source 347 and a positive pressure source 345. The positivepressure source 345 is coupled to a pressure sensor 346, and thenegative pressure source 347 is coupled to another pressure sensor 348.In some specific embodiments, the positive pressure source 345 andnegative pressure source 347 may be accumulators where predeterminedpressures are set therein and vented into the reference volume 324 (viathe valves 344, 341, 350, and 349) to develop specific pressures.

A variable flow/pressure pump 353 is coupled to both of the valves 349and 350 to keep the positive pressure reservoir 345 at a positivepressure and the negative pressure reservoir 347 at a sufficiently lowerpressure. The valves 350 and 349 are also coupled to atmospheric vents354 and 351, respectively. The variable flow/pressure pump 353 is fed asignal at 356, which may be fed back to an output pin for verificationby a processor, e.g., processor 37 of FIG. 2. Also, a switch 355 mayenable and/or disable the pump 353.

In some embodiments, the one or more optical sensors 329 may be used aspart of an inner portion of a control loop that has a target aliquotvolume to deliver. For example, the one or more optical sensors 320 mayprovide a controller within the processor 37 of FIG. 2 (e.g., a PIDcontroller) with an estimate of fill or discharge volume based on thedeflection of the AVS chamber's 335 membrane as measured by the one ormore optical sensors 329. The feedback from the one or more opticalsensors 329 may be used to control the pressure flow or the timing ofthe pneumatics in the AVS pump chamber, e.g., the valves 231, 344, 349,and 350.

Multiple optical sensors 329 may be used to triangulate the AVSchamber's 335 membrane position; additionally or alternatively, themembrane may have reflective features disposed surface of the membraneof the AVS chamber 335 to provide a reflective surface for the opticalsensors 329. In some specific embodiments, an outer portion of thecontrol loop can target the trajectory delivery volume delivered to thepatient to tune the individual aliquot volume. For example, the opticalvolume sensing functionality performed by the one or more opticalsensors 329 may provide an independent volume measurement that is usedas a check on the AVS-based volume measurements and/or to calculateerrors in volume estimation. In additional embodiments, only opticalvolume measurements are performed, i.e., in this specific exemplaryembodiment, no AVS is used).

FIG. 83 shows a flow-controlled membrane pump 358 in accordance with anembodiment of the present disclosure. The flow-controlled membrane pump358 is similar to the pressure controlled pump 322 of FIG. 79; however,the flow-controlled membrane pump 358 does not have the reservoirs 345and 347 as shown in FIG. 79.

FIG. 84 shows a state diagram 359 of the operation of theflow-controlled membrane pump 358 of FIG. 83 in accordance with anembodiment of the present disclosure. The state diagram 359 includesstates 360-368. The states 360-368 are illustrated by FIGS. 85-98.

Referring now to FIGS. 84, 85, and 86, an idle state 360 is depicted inFIGS. 84 and 86 with FIG. 86 showing more details. The idle state 360includes substates 370-371. In substate 370, several variables are set.After a predetermined amount of time after substate 370 sets thevariables, the substate 371 measures several values which are checkedagainst predetermined ranges.

FIG. 85 shows the flow-controlled membrane pump 358 of FIG. 79illustrating the operation of the valves when in the idle state 360 ofthe state diagram of FIG. 84 in accordance with an embodiment of thepresent disclosure. In the idle state 360, the valve 341 couples thereference volume 324 to the atmospheric pressure source 342. Note that,as shown in FIG. 85 which illustrates the idle state 360, the membraneforming the AVS volume 335 is deflated.

As shown in FIG. 86, the substate 370 sets the variables PCadj, PCenb1,PCenb2, PCv1, PCv2, PCv3, HCv1, and HCv2; e.g., via applying an inputvoltage into an appropriate input (see FIG. 83). Referring to FIGS. 85and 86, the variable PCadj sets the pump 353, the variable PCenb1enables the input to the pump 353, the variable PCenb2 enables theswitch 355, the variable PCv1 controls the valve 350, the variable PCv2controls the valve 349, the variable PCv3 controls the valve 341, thevariable HCv1 controls the valve 332, and the variable HCv2 controls thevalve 336.

Also as shown in FIG. 86, after the parameters are set in substate 370,the substate 371 takes several measurements. In substate 371, the PSavs,PSatm, PCmon, OPTvar, OPThv1, OPThc2, and Tavs values are taken andcompared to predetermined ranges. If any of the measured values areoutside a predetermined range, e.g., as shown in the expected column 373in FIG. 86, an error condition 372 is determined to exist; in responseto the error condition 372, an alert or alarm may be issued.

The PSavs is a value determined from the pressure sensor 340, PSatm is avalue determined from the pressure sensor 343, PCmon is a valuedetermined from the sensor 369 to determine if the pump is receiving thecorrect voltage from the input voltage 356, OPTvar is a measurement fromthe optical sensor 329, OPThv1 is the measurement from the opticalsensor 333 to determine if the valve 332 is closed or open, OPThc2 isthe measurement from the optical sensor 337 to determine if the valve336 is open or closed, and Tavs is the measurement of the temperaturefrom the temperature sensor 330.

Referring again to FIG. 84, after the idle state 360, the state diagram359 continues to the positive valve leak test state 361. FIGS. 87-88show the flow-controlled membrane pump 358 of FIG. 83 in use during thepositive pressure valve leak test state of FIG. 84 in accordance with anembodiment of the present disclosure. Note that there is a change in thevalve 349 to allow the pumping of pressure into the reference volume 324from as shown in FIG. 87. FIG. 88 shows where the valve 349 is switchedagain and the reference volume 324 is isolated from the fluid sources.

FIG. 89 shows a more detailed view of the positive pressure valve leaktest state 361 of FIG. 84 in accordance with an embodiment of thepresent disclosure. FIG. 89 may also represent state 364 of FIG. 84. Thepositive pressure valve leak test state 361 includes substates 374-380.

Substate 374 turns on the pump 353 and sets the valves 350, 249, and 341such that positive pressure is applied to the reference volume 324. Thevalves 222 and 337 remain closed. In substate 374, measurements aretaken. If the measured values are outside predetermined acceptableranges, a substate 379 determines an error condition occurs. If theaverage pressure Target Pmax is not reached, state 361 continues to thesubstate 378 to wait for a predetermined amount of time. This process isdepicted in FIG. 87. Substates 374, 375, and 378 may repeat until apredetermined number of substate 378 occurs or a predetermined amount oftime is reached at which time an error 379 is substate determines anerror condition exists.

State 361 may optionally wait a predetermined amount of time whentransitioning from substate 375 to 376. In substate 376, the pump 353 isturned off and the valves 350 and 349 disconnect the variable volume 324from the pump 353 (as depicted in FIG. 88). State 361 may optionallywait a predetermined amount of time when transitioning from substate 376to 377. In substate 377, various measurements are taken, such as an AVSmeasurement using, for example, the AVS system having the speaker 326,and the microphones 327 and 328 which measure the volume of the variablevolume 325 (using an acoustic response) to determine if the AVS volume335 is changing thereby indicating a leak condition. Additionally oralternatively, the optical sensor 330 may detect if a predeterminedmovement of the membrane 335 occurs to determine if a leak conditionexists. If these measurements are outside of a predetermined rangeand/or beyond a predetermined threshold, then an error condition isdetermined to exist in substate 280.

Referring again to FIG. 84, after the positive leak valve test state 361occurs, a negative leak valve test state 362 occurs. Refer to FIGS. 90,91, and 92 for a description of the positive leak valve test state 362.FIGS. 90-91 show the flow-controlled membrane pump 358 of FIG. 83 in useduring the negative pressure valve leak test state of FIG. 84, and FIG.92 shows a more detailed view of the negative pressure valve leak teststate 362 of FIG. 84 in accordance with an embodiment of the presentdisclosure. As shown in FIG. 92, state 362 includes substates 381-387.FIG. 92 may also be used to illustrate state 365 of FIG. 84.

Substate 381 turns on the pump 353 and sets the valves 350, 249, and 341such that negative pressure is applied to the reference volume 324. Thevalves 222 and 337 remain closed. In substate 382, measurements aretaken. If the measured values are outside predetermined acceptableranges, a substate 382 determines an error condition occurs andcontinues to state 385. If the average pressure Target Pmin is notreached, state 382 continues to the substate 386 to wait for apredetermined amount of time. This process is depicted in FIG. 90.Substates 381, 382, and 386 may repeat until a predetermined number ofsubstates 378 occurs or a predetermined amount of time is reached atwhich time substate 385 determines an error condition exists.

State 362 may optionally wait a predetermined amount of time whentransitioning from substate 382 to 383. In substate 383, the pump 353 isturned off and the valves 350 and 349 disconnect the variable volume 324from the pump 353 (as depicted in FIG. 91). State 362 may optionallywait a predetermined amount of time when transitioning from substate 383to 384. In substate 383, various measurements are taken. For example,the AVS system using the speaker 326, and the microphones 327 and 328 tomeasure the volume of the variable volume 325 (using an acousticresponse) to determine if the AVS volume 335 is changing therebyindicating a leak condition. Additionally or alternatively, the opticalsensor 330 may detect if a predetermined movement of the membrane 335occurs to determine if a leak condition exists. If these measurementsare outside of a predetermined range and/or beyond a predeterminedthreshold, then an error condition is determined to exist in substate387.

FIG. 93 shows the flow-controlled membrane pump 358 of FIG. 83 in useduring the fill state 363 of FIG. 84 in accordance with an embodiment ofthe present disclosure. FIG. 94 shows a more detailed view of the fillstate 363 of FIG. 84 in accordance with an embodiment of the presentdisclosure.

State 363 includes substates 388-391. Substate 288 sets the valves 350and 351, and the pump 353 to apply a negative pressure to the variablevolume 324. The valve 332 is also opened and the AVS volume 335 fillswith a fluid from the fluid reservoir 331. State 389 takes severalmeasurements, including an optical measurement from the optical sensor330, to determine if the membrane defining the AVS volume 335 isfilling. If it hasn't filled, substate 391 waits a predetermined amountof time. Thereafter, substates 288, 289, and 391 may be repeated for atleast a predetermined number of cycles and/or until a predeterminedamount of time has passed, after which substate 390 determines that anerror condition exists, e.g., because the reservoir 331 is empty and/ora valve is stuck, for example, valve 332 may be stuck closed, etc.Additionally or alternatively, if the measurement taken during thesubstate 389 is outside of a predetermined range and/or is beyond apredetermined threshold, the substate 390 may determine an errorcondition exists.

Referring again to FIG. 84, after state 363 is performed, anotherpositive valve leak test is performed during state 364 and anothernegative valve leak test is performed in state 365.

State 366 takes an AVS measurement to determine the volume of the AVSchamber 355 (see FIG. 95). Referring now to FIGS. 95 and 96: FIG. 95shows the flow-controlled membrane pump 358 of FIG. 83 in use during anAVS measurement state 366, and FIG. 96 shows a more detailed view of theAVS measurement state 366 of FIG. 84.

State 366 includes substates 392 and 395. Substate 392 causes thespeaker 329 to emit one or more acoustic frequencies, and substate 393takes measurements from the microphones 327 and 328 to determine anacoustic response. The acoustic response is correlated with a volume ofthe AVS chamber 335 and is thus also correlated with the fluid in theAVS chamber 335. The acoustic response and other measurements are takenduring substate 393. Substates 392 and 393 may optionally repeated,e.g., shown as the substate 395. If one or more measurements from thesubstate 392 are outside of a predetermined range and/or is beyond apredetermined threshold, the substate 394 may determine that an errorstate exists.

Referring again to FIG. 84, after the AVS measurements are taken instate 366, the emptying state 367 empties the AVS volume 335. FIG. 97shows the flow-controlled membrane pump 358 of FIG. 83 in use during theemptying state 367 of FIG. 84, and FIG. 98 shows a more detailed view ofthe emptying state of FIG. 84.

As shown in FIG. 98, the emptying state 367 includes substates 396-399.Substate 396 sets the valves 350 and 349, and the pump 353 to apply apositive pressure to the reference volume 324. Substate 396 also openthe valve 336 to allow fluid to flow to the patient 338. During substate387, several measurements are taken, and substate 397 continues tosubstate 399 to wait a predetermined amount of time. The substates 396,397, and 399 repeat until the optical sensor 329 determines that the AVSvolume is below a predetermined amount. If the measurements taken duringsubstate 397 are outside of a predetermined range and/or a measurementexceeds a predetermined threshold (i.e., above or below the threshold)the substate 398 determines an error condition exists. If the substate399 repeats a predetermined number of times and/or operates for apredetermined amount of time, the substate 398 may determine that anerror condition exists, e.g., a stuck valve such as valve 336 and/or adownstream occlusion may be preventing the AVS volume from dischargingthe liquid to the patient 338, for example.

Referring again to FIG. 84, after state 367, state 368 takes an AVSmeasurement. The AVS measurement 368 may be compared to the AVSmeasurement 366 to determine an amount of fluid delivered to a patient338. For example, in the emptying state 367, some of the fluid mayremain in the AVS volume 335. By comparing the difference between theAVS measurements, the amount of fluid discharged down the line to thepatient 338 may be estimated.

FIG. 99 shows a membrane pump 411 having an elastic membrane 412 that isflush with a disposable portion 413 and applies force to a liquid inaccordance with an embodiment of the present disclosure. That is, theaction of the membrane 412 provides an actuation to move fluid throughthe membrane pump 411. The membrane pump 411 includes an AVS assembly417 that couples to a disposable portion 418. The AVS assembly 417 maybe snap-fitted, may screw onto, or may include latches to attach to thedisposable portion 418. The membrane pump 411 includes a pneumatic fillport 414. The pneumatic fill port 414 may be connected to any air pumpas described herein. In yet additional embodiments, the pneumatic fillport 414 may be connected to a liquid pump, e.g., a syringe pump, orother liquid pump. In some embodiments, alternative positive andnegative pressures are applied to the pneumatic fill port 414, which isused in conjunction with valves 415 and 416 to pump fluid. In someembodiments, a negative pressure is applied to the pneumatic fill port414 and the elastic property of the membrane 412 is used to suck inliquid through the valve 416. In some embodiments, a positive pressureis applied to the pneumatic fill port 414 and the elastic property ofthe membrane 412 is used to expel in liquid through the valve 415.

FIGS. 100-101 show two embodiments of lung pumps in accordance withembodiments of the present disclosure. FIG. 100 shows a lung pump 419,and FIG. 101 shows a lung pump 420.

The lung pump 419 of FIG. 100 includes a rigid body 421 having an AVS orFMS port 425 for measuring the volume of a reservoir 425 that isflexible. FMS is described in the U.S. Pat. Nos. 4,808,161; 4,826,482;4,976,162; 5,088,515; 5,193,990; and 5,350,357. In some embodiments,positive and/or negative pressure is applied to the port 425 tofacilitate the pumping action of the lung pump 419. The reservoir 424 isin fluid communication with the valves 422 and 423. The reservoir 424may be molded or bonded to the tube 431, or is vacuum formed from thetube 431, e.g., a blister. The rigid body 421 may fully seal around thetube 431 as it passes through the rigid body and connects to thereservoir 424. By applying a positive or negative pressure via the port425, the fluid may be drawn into and out of the reservoir 424. Thispositive and negative pressure may be supplied by a manifold which alsocontains a reference chamber allowing for FMS measurements via the port425. Additionally or alternatively, the rigid body 421 may includehardware, such as, for example, a processor to control the valves 422and 425, an AVS assembly coupled to the port 425, etc. The liquid isdrawn from the valve 422 and leaves via the valve 423. The valves 422and 423 may be pinch valves. The valves 422 and 423 may be alternativelyclosed and open, relative to each other and synchronized with anypositive and/or negative pressure applied via the port 425. For example,a pumping sequence may occur as follows: (1) close the valve 413 andopen the valve 422; (2) apply a negative pressure to the port 425; (3)close the valve 422; (4) estimate the volume of fluid in the reservoir425 (e.g., using AVS or FMS); (5) repeat steps (1)-(4) until apredetermined volume is within the reservoir; (6) open the valve 425;(7) apply a positive pressure to the valve 425; (8) close the valve 423;(9) estimate the volume of fluid in the reservoir; (10) compare thevolumes measured during steps (9) and (4) to determine an amount ofliquid discharged; (11) and repeat (1)-(10) until a predetermined amountof liquid has been pumped.

The lung pump 420 of FIG. 101 includes a rigid body 426 having an AVS orFMS port 430 for measuring the volume of a reservoir 429 that isflexible. In some embodiments, positive and/or negative pressure isapplied to the port 430 for facilitating the pumping action of the lungpump 420. The reservoir 429 is in fluid communication with valves 427and 428. The lung pump 420 may be similar to the lung pump 419 of FIG.99; however, the valve 427 is opened and the valve 428 is closed to pumpfluid into the reservoir; and the valve 428 is opened and the valve 427is closed to pump fluid out of the reservoir.

FIGS. 102-104 show several gaskets for sealing a lung pump in accordancewith additional embodiments of the present disclosure. FIG. 102 shows atube 432 that may be sealed by sections 433 and 434 of the rigid body ofthe lung pump (e.g., rigid body 421 of FIG. 99 or rigid body 426 of FIG.100). In other embodiments, 422 and 424 may be part of a housing,latching, or dooring mechanisms. FIG. 103 shows a tube 425 that includesa gasket seal 426. The gasket seal 426 may push to the left and rightcausing a better seal where the two sides of the sealing surfaces meet(i.e., 422 and/or 424). FIG. 104 shows another way of sealing a tube 432in including a gasket 427 that seals by being compressed in between avalley structure 427 and a compressing plate 429.

FIG. 105 shows another lung pump 430 in accordance with anotherembodiment of the present disclosure. The lung pump 430 includes a rigidpiece 431 bonded around a tube 432 that creates a face-sealing gasketthat seals against a ring structure 433 when a pressure is applied tothe rigid piece 431. The rigid piece 431 may be a circular structure,e.g., a ring structure similar to a washer.

FIGS. 106-112 illustrate the operation of a piston pump while performingvarious checks in accordance with an embodiment of the presentdisclosure. The checks described in conjunction with the piston pump ofFIGS. 106-112 may also be used with a peristaltic pump having aspring-biased plunger as described herein. FIG. 106 shows a pump 434including a piston 435, a diaphragm 436, an inlet valve 437, an outletvalve 438, and a pump chamber 439. The piston 435 may be coupled to alinear actuator 54 (not shown in FIGS. 106-112) that is coupled to aprocessor 37 for control (see FIG. 3).

The opening of the valves 437 and 438 may be timed with the movement ofthe piston 435 to allow the integrity of the valves to be checkedperiodically during the pump operation. The piston 435 applies apressure or vacuum to check the valves 437 and 438 to verify that one orboth are not leaking before opening the other valve. This process may beused to safeguard against free-flow conditions; if one valve is notsealing properly the other valve is not opened. The same configurationcan be used to check for air in the pumping chamber, upstreamocclusions, and downstream occlusions.

In some embodiments, the piston 435 and valves 437 and 438 may be drivenby a set of cams driven by a single motor. Additionally, in someembodiments, the piston 435 is spring loaded such that the cam lifts thepiston 435 and the spring returns the piston 435 to the down position;this specific embodiment may have a relatively constant deliverypressure.

In some embodiments of the present disclosure, the position of thepiston 435 and/or the position of the diaphragm 436 may be determinedusing a sensor. In some embodiments, the position of the piston 435 maybe determined using an encoder, a magnetic sensor, a potentiometer, orrotational sensors on a camshaft, etc. In additional embodiments, theposition of the piston 435 is measured directly by using an opticalsensor, a LVDT (linear variable differential transformer) sensor, ahall-effect sensor, or other linear sensor. The position of thediaphragm 436 may be sensed using an AVS assembly as described elsewhereherein (e.g., the AVS assembly 417 of FIG. 98 may be used to determinethe position of the diaphragm 436). In some additional embodiments, nopiston is used and the diaphragm is moved using pneumatic pressure asdescribed herein.

FIGS. 107-112 illustrate various stages of the piston pump of FIG. 106.FIG. 107 illustrates an air check and inlet valve 437 leak check. Thepiston 435 applies a downward force while the valves 437 and 438 areclosed. If the piston 435 moves a predetermined distance and/or beyond apredetermined speed, the processor 37 may determine that excessive airexists within the pump chamber 439. If the piston 435 compresses anamount and slowly continues to move towards the bottom of the pumpchamber 439, the processor may determine that one of the valves 437and/or 438 is leaking. For example, if a valve 437 and/or 438 isleaking, the volume with the pump chamber 439 will continuouslydecrease. The movement (or speed) cause by excessive air in the pumpchamber 439 may be at a different speed than the movement caused by aleak; and, in some specific embodiments, the processor 37 maydistinguish between excessive air in the pump chamber 439 and/or a leakin one of the valves 437 and 438. For example, the piston 435 may movedownwards at a first speed and quickly approaches a very slow speed; ifthe slow speed continues, then it may be determined that the continuedslow movement after the abrupt negative acceleration is an indication ofa leak in one of the valves 437 and 438.

FIG. 108 shows a stage in which a downstream occlusion check isperformed. The outlet valve 438 is opened and the fluid in the pumpchamber 439 is delivered to the patient. If the volume does not change,there may be a downstream occlusion. Additionally or alternatively, ifthe piston 435 moves slower than a threshold and/or moves more slowlythan the previous fluid discharge by a predetermined amount, theprocessor 37 (see FIG. 3) may determine that a downstream occlusion hasoccurred. Additionally or alternatively, if the piston 435 stops movingless than a predetermined amount of movement (e.g., with a predeterminedforce is applied to the piston 435) then the processor 37 may determinethat a downstream occlusion has occurred.

FIG. 109 illustrates the stages in which the outlet valve 438 is closed.FIG. 110 illustrates the stage in which the piston 435 is pulled up. Theoutlet valve 438 remains closed. The stretch of the diaphragm 436results in vacuum in the pump chamber 439. If one of the valves 437 and438 is leaking, the fluid in the pumping chamber 439 will increase. Ifthe diaphragm 436 moves by a predetermined amount, the processor 37 maydetermine that a valve is leaking and issue an alert and/or alarm.

FIG. 111 illustrates a stage where the pump chamber 438 is filled, andan upstream occlusion check is performed. The inlet valve 437 is openedand the pump chamber fills 438 with liquid. If the pump chamber fails tofill by a predetermined amount, then the processor may determine that anupstream occlusion exists or the IV bag is empty. Additionally oralternatively, if the chamber fills 438 too slowly, or slower than theprevious fill by a predetermined amount, the processor 37 may determinethat an upstream occlusion exists. FIG. 112 illustrates the stage inwhich the inlet valve 437 is closed. The stages illustrated in FIGS.107-112 may be repeated until a predetermined amount of fluid isdelivered to a patient.

FIGS. 113 and 114 illustrate a piston pump 441 in accordance withanother embodiment of the present disclosure. As shown in FIG. 113,piston pump 441 includes a disposable cassette 442 including a preformedmembrane 440 and a cassette body 445. The preformed membrane 440 may beone or more of a PVC elastomeric such as, Sarlink, Pebax, Kraton, aSantoprene, etc. The preformed membrane 440 may be attached to thecassette body 445 using any method, including heat bonding, laserwelding, using a solvent or adhesive bonding, ultrasonic welding orattachment, RF welding, or over molding. When the preformed membrane 440is compressed, as shown in FIG. 114, the membrane will return to itsoriginal shape as shown in FIG. 113 after the piston 443 is withdrawn.FIGS. 115 and 116 show two views of a cassette 444 having severalmembrane pumps 441. The cassette 444 may be formed by a rigid bodydefining the cassette body with two elastic layers disposed around therigid body. The rigid body may form the reservoir such that the elasticlayer forms the preformed membrane as illustrated in FIGS. 113 and 114.

FIG. 117 shows an assembly 446 having a cassette 447 that includes amembrane pump 451 and volcano valves 449 and 450 in accordance with anembodiment of the present disclosure. The membrane pump 451 includes apump plunger 452 that interfaces with an membrane 451. As the plunger451 reciprocates, fluid is draw from the fluid path 454 and out thefluid path 456. The volcano valve 449 is a one way valve that allowsfluid into the fluid volume 455 from the volcano valve 449, but not inreverse. An actuator may press again the membrane 456 in someembodiments to help the one-way action of the volcano valve 449.

The volcano valve 450 is a one-way valve that allows fluid out of thefluid valve 455 through the fluid path 455 and the volcano valve 450(but not in reverse). An actuator may press again the membrane 457 insome embodiments to help the one-way action of the volcano valve 450.

The assembly 446 also includes an AVS assembly 448. The AVS assemblyincludes a reference volume 458 having a speaker 459 and a microphone460. The variable volume 461 includes a microphone 462. The speaker 459and the microphones 460 and 462 are coupled to a processor 37 to measurethe volume of the fluid volume 455 and coordinate the operation of theplunger 452 as described herein.

The plunger 452 may interface with one or more acoustic seals coupled tothe AVS assembly 448. The processor 37 may be in operative communicationwith a position sensor (e.g., one coupled to a linear actuator of theplunger) to determine the position of the plunger 452. The processor 37may account for the amount of volume the plunger 37 displaces as itreciprocates in and out of the variable volume 461; this volumecorrection may be done by directly measuring the plunger's (452)displacement or by measuring the a drive shaft angle coupled to a camthat moves the plunger 452.

FIG. 118 shows a roller mechanism 463 of a cassette-based pump inaccordance with an embodiment of the present disclosure. The rollermechanism 463 includes rollers 464, 465, and 466. The rollers 464, 465,and 466 move in a circular direction and apply a downward pressure againa cassette 467 having a cassette body 468 and a membrane 469. Therollers 464, 465, and 466 may be on a rail and may be spaced such thatat least one roller engages the cassette 467. The roller mechanism 463may be controlled by a stepper motor. The roller mechanism 463 may helppump liquid at a rat of, for example, 0.1 ml/hr.

The roller mechanism 463 may be used to estimate fluid flow based uponthe speed of its movement, for example. The rollers 464, 465, and 466may be disengaged from the cassette 467 to facilitate non-occluded flowand/or to create a desired free-flow condition.

FIG. 119 shows the fluid paths 470 of a cassette-based pump for use withthe roller mechanism of FIG. 118 in accordance with an embodiment of thepresent disclosure. The fluid paths 470 include a roller interactionarea 471 having a path 472 and a bypass path 473. The fluid paths 470may included a vacuum formed film bonded to a ridged back to form raisedflexible features. The path 470 includes occluders 474 and 475. Theoccluders 474 and 475 may be independently occluded. The paths 472 and473 may have the same or different cross-sectional areas. The rollermechanism 463 may interact with the roller interaction area 472 tocreate different flow rates based on the rate of movement of the rollermechanism 463 and the total cross sectional area of all channels thatare un-occluded (e.g., which of the occlude features 474 and 475 areengaged. The occluder features 474 and 475 may be volcano valves with aplunger that may be applied on the membrane of the volcano valve to stopfluid from flowing in any direction. In other embodiments, the occluders474 and 475 may be a pinch valves coupled to an actuator, such as asolenoid.

The fluid paths 470 may include a fluid capacitor 476 to buffer the flowof liquid (e.g., smooth the liquid). Additionally or alternatively, anAVS assembly may be coupled to the fluid capacitor 476 to measure fluidflowing therethrough.

In another embodiment, one or more of the fluid paths 472 or 473 includea flat flexible film boded to a ridged back with the features moldedinto the rigid backing (cassette body). In this embodiment, the roller463 has a feature that recesses into the channel 478 in order to pinchoff the channel 478. This embodiment may also have molded-in featuresthat allows a ball-head piston to variably restrict the flow through thechannel 478 (e.g., the occlude features 474 and 475). The geometry ofthe features that recess into the channels and the piston head may beadjusted to allow different flow profiles based on the linear engagementof the piston. In one embodiment, the disposable has one channel 472 forthe roller mechanism 463 and a second channel 473 that acts as a bypassfrom the roller area. The two channels 472 and 473 in conjunction withthe occluders 474 and 475 allow the cassette (which may be disposable)to be used in a bypass mode or a pump mode. In some embodiments, theroller mechanism 463 of FIG. 119 is always engaged above the channel 478but not over the bypass channel 473.

In one embodiment, the roller mechanism 463 may be used for high flowrates and the bypass 474 may be used for low flow rates. For example, insome specific embodiments, when the fluid paths 472 and 473 have a crosssectional area of 0.4 cm², the flow rates may be from 100 ml/hr to 1000ml/hr by using a stepper motor to actuate the linear travel of therollers from 250 cm/hr to 2500 cm/hr; the bypass 473 is used to achieveflow rates under 100 cm/hour.

FIG. 120 shows the fluid paths 478 of a cassette-based pump for use withthe roller mechanism of FIG. 118 in accordance with an embodiment of thepresent disclosure. The fluid paths 478 include two paths 479 and 480,and a bypass path 481 The roller mechanism 470 of FIG. 118 interfaceswith the fluid paths 470 and 480. The fluid paths 478 are also coupledto occluders 482, 483, and 484.

FIG. 121 shows the stages 310, 311, and 312 of an infiltration test inaccordance with an embodiment of the present disclosure. Theinfiltration test illustrated by FIG. 121 includes an occluder roller313 that is pressed against a tube 314 (as shown in stage 311) which isthen drawn back through a rolling motion (shown in stage 314). Theoccluder roller 313 may be in the pumps 19, 20, and/or 21 (see FIG. 1)or in the infusion site monitor 26 (See FIG. 2). The monitoring client 6can instruct the occluder roller 313 to perform an infiltration test.For example, the monitoring client 6 may instruct a stepper motorcoupled to the roller occluder 313 to pull liquid out of the patient 5(See FIG. 1). The monitoring client 6 may then receive an estimate ofthe amount of blood that enters into the infusion site monitor 26 (seeFIG. 1) from the infiltration detector 32 (see FIG. 2). The infiltrationdetector 32 determines if the proper amount of blood is pulled into theinfusion site monitor 26 during the stages of the infiltration test, oralternatively, the monitoring client 6 may receive raw data from theinfiltration detector 32 to determine if the proper amount of blood ispulled into the infusion site monitor 26 (See FIGS. 1 and 2).

As previously mentioned, the infiltration detector 32 of FIG. 2 may be acamera-based infiltration detector 32 as described above in relation tothe system 108 of FIG. 33 when used to capture images illustrated byFIGS. 37 and 38. FIGS. 37 and 38 illustrate the images taken by thecamera 109 of the system 108 of FIG. 33 for estimating blood that entersinto the infusion site monitor 26 of FIG. 2 during an infiltration test.That is, the system 108 of FIG. 33 may be within the infiltrationdetector 32 of the infusion site monitor 26 (see FIG. 2) for detectingblood when the roller occluder 313 of FIG. 121 actuates to draw bloodinto the infusion site monitor 26 of FIG. 2.

During stage 312, a drawback volume 315 thereby is pulled from a patient5. A camera 109 of FIG. 33 at an infusion site monitor 26 (e.g., withinthe infiltration detector 32) may determine if blood is drawn back fromthe patient as shown in FIGS. 37 and 38. If no blood is pulled into thetube within the infusion site monitor 26 (see FIG. 2), it may be anindication that an infiltration has occurred. Additionally oralternatively, the camera 109 of FIG. 33, in conjunction with a pressuresensor 33 and/or volume sensor 169, may be used to determine what amountof pressure causes the blood to be pulled back into the tube 41.

In some embodiments, the fluid is returned to the patient 5 by actuatingthe rolling occluder 313 in the opposite direction, or by lifting theoccluder 313 off of the tube 314. In an additional embodiment, acompliant upstream reservoir may be included which holds the drawbackfluid (valves may direct the reverse fluid into the complaint upstreamreservoir). The upstream reservoir may be coupled to an AVS chamber asdescribed herein or is a separate chamber. The AVS chamber may have thedrawback fluid volume measured by a processor coupled thereto and/orcommunicated to the monitoring client 6. Additionally or alternatively,the pumps 19, 20, and 21 are stopped during an infiltration test or mayassist in draw back fluid, in conjunction with the rolling occluder 313or in lieu of the rolling occluder 313.

In additional embodiments, a compliant chamber is used between theroller occluder 313 and the patient 5. The displacement volume of thechamber membrane during the drawback is monitored using, for example,AVS or an optical sensor. The deflection of the chamber membrane isproportional to the pressure in the fluid line 314, the amount of thedeflection of the membrane is proportional to the effort to draw bloodinto the tubing. A threshold amount of drawback pressure needed to drawblood out of the patient 5 is used to determine if an infiltrationexists. In addition, if a threshold amount of time is required todrawback, this may be used as an indication that a downstream occlusionexists or an infiltration exists. Therefore, the chamber membrane couldbe monitored over time and detect a rate in pressure change that is anindication of the drawback effort (as determined by the processor 37 ofFIG. 2).

FIG. 122 shows stages of an infiltration test 316 and 318 in accordancewith an embodiment of the present disclosure. A piston 319 may bedisposed anywhere along the fluid line or in a pump 19, 20 or 21 of FIG.2, or the piston 319 may be disposed in the infusion site monitor 26 ofFIG. 2. In stage 316, a valve 318 remains open and the piston 319 ispress against a membrane 320, but fluid continues to flow to thepatient. In stage 317, the valve 318 is closed, and the piston 319 islifted up, after which the resiliency of the membrane 320 pulls back anddraws fluid backwards. The drawn back fluid returns to the patient whenthe piston actuates back to the resting state as shown in stage 316. Acamera 109 of FIG. 33 at an infusion site monitor 26 in the infiltrationdetector 32 (see FIG. 2) may determine if blood is drawn back from thepatient 5 as described above. If no blood is pulled into the tube withinthe infusion site monitor 26 (see FIG. 2), it may be an indication thatan infiltration has occurred.

In some embodiments, the elastomer surface area and elastomer propertiesare selected in combination with the chamber volume such that there is amaximum determined fluid pressure that is applied during the drawback,e.g., the properties may be chosen such that there is sufficientdrawback pressure to draw back blood into the monitoring area, however,there would be insufficient pressure to draw back the blood into themonitoring when an infiltration has occurred. Additionally oralternatively, the blood must be drawn back within a predeterminedamount of time; otherwise, an infiltration condition may be determinedto exist. The amount of time allowed for the drawback can be used withpredetermined criteria to determine if an infiltration has occurred(i.e., allow the drawback chamber to persist with drawback for apredetermined amount of time while looking for the indication of bloodusing the camera 109, and determining that an infiltration has occurredif no blood is detected by the infiltration sensor 32 (see FIGS. 2 and33), e.g., a camera 109, before the predetermined amount of time haspassed).

FIGS. 123 and 124 show a cell-based reservoir 485 in accordance with anembodiment of the present disclosure. The cell-based reservoir 485 maybe the reservoirs 2, 3, or 4 of FIG. 1. The cell-based reservoir 485includes cell foam 486 capable of absorbing liquid constructed of acompatible material to dampen the motion of an infusate. The cell foam486 may include a membrane 487. The reservoir base 488 may beconstructed using a in a rigid, semi-rigid, or non-rigid fluid reservoirto increase infusate stability in the presence of fluid shear.

For example, when using a semi-rigid base 488, the cell foam 486 mayinclude an open-cell silicone foam to fill the normally empty reservoircavity. The cell foam 486 may help prevent sloshing of the reservoircontents to help preserve the stability of the infusate in someembodiments. By choosing a foam with a high degree of compressibilityrelative to both the collapsible membrane's 487 spring rate and thepumping mechanism, the residual volume of the cell foam 486 may beminimal in some embodiments.

FIGS. 125 and 126 show a tube-based reservoir 489 in accordance with anembodiment of the present disclosure. The cell-based reservoir 489 maybe the reservoirs 2, 3, or 4 of FIG. 1. The tube-based reservoir 489includes a tubing reservoir 490 that can house a liquid. The tube-basedreservoir 489 may be vented through a filter 491. The filter 491 may bepart of the vent of FIGS. 51-55. For example, a pumping mechanism (e.g.,a pump as described herein but not shown in FIGS. 125 and 126) may drawfluid from the tubing reservoir 490 stored in a rigid reservoir cavity492 (the base 492 may be flexible, rigid, semi-rigid, and/or part of acassette in some embodiments). The tubing reservoir 490 can help preventsloshing of the reservoir contents thereby helping preserve infusatestability in some embodiments.

FIG. 127 shows stages 1-8 illustrating a method for operating a plungerpump 493 in conjunction with an AVS assembly 494 in accordance with anembodiment of the present disclosure. A fluid path 495 includes valves496, 497, and 498.

Stage 1 shows the valve 498 closed with valves 496 and 497 open. Thevalve 497 may be closed while the plunger 499 withdraws to check if thevalves 498 and 497 are leaking. For example, a constant force may beapplied to the plunger 499 drawing the plunger up (e.g., from a spring)and either valves 496 and/or 497 may be closed. If the plunger 499 movesupwards beyond a predetermined amount or more quickly than predeterminedspeed, the processor 37 (see FIG. 2) may determine that a leak hasoccurred. Additionally or alternatively, the valve 496 may be closed,and the plunger 499 applies an upwards force by a predetermined amountof time and then applies a downward force. The AVS assembly 494 may thenperform an AVS sweep. If the fluid within the AVS assembly (e.g.,measured by the volume of the fluid volume) is beyond a predeterminedamount) then the processor may determine that one of the valves 496 and498 may be leaking.

Stage 2 shows the fluid being drawn into the plunger pump 493. Stage 3performs an AVS sweep. Between stages 3 and 4, a leak check may beperformed, e.g., the valves 497 and 498 may remain closed while theplunger 493 applies a downwards force. If there is movement beyond apredetermined amount, the one or both of the valves 497 and 498 may bedetermined to be leaking by the processor. In Stage 4, the volume offluid from the plunger pump 493 is transferred to the membrane of theAVS assembly 494. Stage 5 there is an AVS sweep to determine the fluidin the AVS assembly 494. In stage 6, the valve 497 is opened, and thevolume of fluid is transferred from the AVS assembly 494 to the plungerpump 493. Between stages 5 and 6, the valve 497 may temporarily be leftclosed to perform another valve leak check.

In stage 7, the valve 497 is closed. In stage 8, the fluid in theplunger pump 493 is discharged. Between stages 7 and 8, the valve 498may initially remain closed to determine if one or both of the valves497 and 498 is leaking.

FIG. 128 shows several stages illustrating a method for operating aplunger pump in conjunction with an AVS assembly in accordance withanother embodiment of the present disclosure. Between stages 1 and 2, aleak test may be performed by keeping the valve 500 temporarily closedwhile an upwards force is applied to the plunger 499. In stage 2, fluidis drawn into the plunger pump 493. Also during stage 2 an AVS sweep maybe performed by the AVS assembly 494. In stage 3, the fluid istransferred to the AVS assembly 494. Also during stage 2 an AVS sweepmay be performed by the AVS assembly 494. A leak test may be performedbetween stages 2 and 3 (e.g., by keeping the valve 501 closed whileapplying a downward force on the plunger 499. In stage 4, the fluid isdrawn from the AVS assembly 494 into the plunger 493. Also during stage2 an AVS sweep may be performed by the AVS assembly 494. Between stages3 and 4, a leak test may be performed by keeping the valve 501temporarily closed while an upwards force is applied to the plunger 499.In stage 5, the fluid is discharged from the plunger 493 to the patient(i.e., past the AVS assembly 494). A leak test may be performed betweenstages 4 and 5, by keeping the valve 501 temporarily closed and/or tocheck for backflow. A leak test may also be performed during stage 5 tocheck for backflow.

FIG. 129 shows several stages illustrating a method for using a plungerpump 503 having an AVS assembly 504 in accordance with an embodiment ofthe present disclosure. In stage 1, an AVS sweep is performed. In stage2, fluid is drawn into the variable volume 506. In stage 2, after fluidis drawn into the variable volume 453, another AVS sweep is performed.In stage 3, the fluid is discharged. In stage 3, after the fluid hasdischarged, an AVS sweep may be performed. Note that the actuator 507 iswithin the variable volume 506. Therefore, the movement of the actuator507 does not affect the volume of the variable volume 506.

FIG. 130 shows several stages illustrating a method for using a plungerpump 508 having an AVS assembly 509 in accordance with an embodiment ofthe present disclosure. The actuator 507 is located outside of thevariable volume 509. The plunger pump 508 uses a standard IV set 510such that the compliance of the tubing 510 draws liquid in during stage4. Stage 2 discharges the liquid. The stages 1-4 may be repeated.

Stage 1, an AVS sweep is performed by the AVS assembly 509 and adownward force may be applied to the plunger 512 with both of the pinchvalves 513 and 514. In stage 2, the fluid volume is discharged. In stage3, the plunger 512 is retracted, after which an AVS sweep may beperformed to determine if the valves 513 and 514 are leaking (e.g., thecompliance of the tubing 455 may provide a negative pressure within thetubing 510.

FIG. 131 shows several stages 1-5 illustrating a method for using aplunger pump 515 having an AVS assembly 516 in accordance with anembodiment of the present disclosure. The plunger pump 515 draws fluidinto and out of the variable volume 517 via a pneumatic actuator 518.During stage 1, a positive and/or negative pressure may be applied tothe variable volume 518 with both of the valves 519 and 520 closed.During stage one, one or more AVS sweeps may be performed by the AVSassembly 516. If the volume estimated by the AVS assembly 516 changeswhen both of the valves 519 and/or 520, then the processor 37 maydetermine that a leak in one or both of the valves 519 and/or 520exists.

During stage 3, a positive and/or negative pressure may be applied tothe variable volume 518 with both of the valves 519 and 520 closed.During stage one, one or more AVS sweeps may be performed by the AVSassembly 516. If the volume estimated by the AVS assembly 516 changeswhen both of the valves 519 and/or 520, then the processor 37 maydetermine that a leak in one or both of the valves 519 and/or 520exists.

FIG. 132 shows a plunger pump 521 with an actuator 522 inside thevariable volume 523 for use with a standard IV set tubing 524 inaccordance with an embodiment of the present disclosure.

FIG. 133 shows several views of a cam-driven linear peristaltic pump 522having pinch valves 523 and 524 and a plunger 525 inside a variablevolume 536 in accordance with an embodiment of the present disclosure.The cross-sectional views 527 and 528 show two different standard IV settubing 529 configurations below the plunger 525.

FIG. 134 shows a plunger pump 530 for use within a standard IV 531 settubing with an actuator 532 outside of the variable volume 533 inaccordance with an embodiment of the present disclosure. FIG. 135 showsseveral views of a cam-driven linear peristaltic pump 534 having pinchvalves 535 and 536 a plunger 537 inside a variable volume 538 with acorresponding cam mechanism 539 outside of the variable volume 538 inaccordance with an embodiment of the present disclosure. As the camfollowers 540, 541, and 542 move in and out of the variable volume 535,the processor 37 of FIG. 2 may adjust the measured volume to account forthe changes in volume the cam followers 540, 541, and 542 affect thevariable volume. Cross-section views 543 and 544 show two differentconfiguration of the standard IV set tubing 545 for the plunger 537 tointerface with.

FIG. 136 shows a plunger pump 546 having a plunger 547 inside a variablevolume 548 with an actuator 549 outside of the variable volume 548 inaccordance with an embodiment of the present disclosure. The processor37 is coupled to a position sensor of FIG. 2 to account for the volumeof the shaft of the plunger 547 as it moves in and out of the variablevolume 548.

FIG. 137 shows a cam-driven linear peristaltic pump 550 having a plunger551 inside a variable volume 552 with a corresponding cam mechanism 553outside of the variable volume 552 and pinch valves 554 and 555 on thehousing of the variable volume 552 in accordance with an embodiment ofthe present disclosure. The pinch valves 554 and 555 may also form theacoustic seal for interface of the variable volume 552 and the standardIV set tubing 556. Two cross-sectional views 557 and 558 are shown toillustrate the configuration of the interface of the plunger 551 withthe standard IV set tubing 556.

FIG. 138 shows a plunger pump 559 having a plunger 560 inside a variablevolume 561 and pinch valves 562 and 563 outside of the variable volume561 in accordance with an embodiment of the present disclosure. Theactuator 564 (e.g., a cam mechanism, linear motor, linear actuator,etc.) is located outside of the variable volume 561. The processor 37 ofFIG. 2 can compensate for the shaft of the plunger 560 as it enters andexits the variable volume 561.

FIG. 139 shows several views of a cam-driven linear peristaltic pump 562having a plunger 563 inside a variable volume 564 with a correspondingcam mechanism 565 and pinch valves 566 and 567 outside of the variablevolume 564 in accordance with an embodiment of the present disclosure.Views 569 and 570 shows two different configuration of the standard IVset tubing 568. The standard IV set tubing 568 may be positioned by araceway (e.g., defined below, above, and/or around the tubing 568).

FIG. 140 illustrates the stages 1-5 of occlusion detection using aplunger pump 571 having an AVS assembly 572 and a spring-biased pinchingmechanism 573 inside the variable volume 574 in accordance with anembodiment of the present disclosure. The plunger pump 571 includespinch valves 575, 576, and 577.

In stage 1, the pinch valves 575, 576, and 577 are closed. The variablevolume 574 may be measured as the spring-biased pinching mechanism 573compresses the tube 578. If the volume of the variable volume increases(e.g., the tube diameter within the variable volume 574 decreases) thenthe processor 37 of FIG. 2 may determine that one or both of the valves576 and 577 are leaking. Additionally or alternatively, thespring-biased pinching mechanism 573 may include a sensor to estimatethe volume of the liquid within the tube 573 within the variable volume574. The sensor may be, for example, a linear hall effect sensor. If thesensor indicates that the pinching mechanism 573 is slowly closingdespite that the pinch valves 575, 576, and 577 are closed, theprocessor 37 may determine that an error condition exists (see FIG. 2).

In stage 2, the valve 576 is opened and the actuator 579 compressesagainst the tube 573 thereby filling the tube within the variable volumewith a liquid. In stage 3, the valve 576 is closed. In stage 4, thevalve 577 is opened. If there is no occlusion the liquid within thespring-biased pinching mechanism 573 will discharge the liquid. In FIG.137, the stage 4 shows a view 580 where there is no occlusion and thespring-biased pinching mechanism 573 discharges the liquid, and stage 4also shows a view 581 where the spring-biased pinching mechanism 573does not discharge (or does not fully discharge) the liquid. In someembodiments of the present disclosure, the position of thenspring-biased pinching mechanism 573 during stage 4 is used to determineif an occlusion condition downstream exists (e.g., the processor 37 maydetermine that an occlusion exists). Stage 5 shows two views 582 and583. View 582 of stage 5 shows when no downstream occlusion exists andview 583 shows stage 5 when a downstream occlusion exists) note thedifference volumes of the spring-biased pinching mechanism 573 in thetwo views 582 and 583). An AVS sweep and/or the position sensor of thespring-biased pinching mechanism 573 may be used in stage 5 to determineif the volume of the liquid within the variable volume 573 exceeds apredetermined threshold such that the processor 37 of FIG. 2 determinesthat a downstream occlusion exists.

FIG. 141 shows a pump 600 with a spring-loaded plunger 604 within avariable volume 605 of an AVS assembly 606 with actuated plunger 604outside of the variable volume 605 in accordance with an embodiment ofthe present disclosure. The valve 602 may be closed and the valve 601opened with the plunger 604 retracted to allow the tube 607 to pullfluid in under the plunger 604.

The valves 601 and 603 are closed and the valve 602 opened while theplunger 604 presses against the tube 607 to force fluid into the tube607 region disposed within the variable volume 605; this causes thespring-loaded (or spring-biased) plunger 604 actuate to increase theamount of energy stored in its spring. The valve 602 is closed and anAVS measurement is taken. Thereafter, the pinch valve 603 is openedwhich forces fluid within the variable volume 605 out of the tube 607and towards the patient. Thereafter, the valve 602 is closed and anotherAVS sweep is performed. The AVS volume measurements are compared todetermine the amount of fluid discharged through the pump 600. Thespring biased plunger 604 may be a single plunger with a spring attachedto a shaft to apply a downward force on the tube 607.

FIG. 142 shows a linear peristaltic pump 608 with pinch valves 609 and610 and a cam shaft 611 disposed within a variable volume 612 of an AVSassembly 613 having spring-biased pinching mechanism 614 (see view 615)disposed therein, and a plunger 616 and a pinch valve 617 outside of thevariable volume 612 in accordance with an embodiment of the presentdisclosure. The manner of operation may be the same as the pump 600 ofFIG. 141 (e.g., the plunger 616 force fluid to expand thepinching-mechanism 614 and load the associated springs).

FIG. 143 shows a linear peristaltic pump 618 with pinch valves 619, 620,and 621 and a plunger 622 disposed outside of a variable volume 623 ofan AVS assembly 624 in accordance with an embodiment of the presentdisclosure. The manner of operation may be the same as in pump 600 ofFIG. 141.

FIG. 144 shows a the stages 1-5 of a plunger pump 625 having an opticalsensor or camera 626 to measure the volume within a tube 627 residingwithin a chamber 628 in accordance with an embodiment of the presentdisclosure. The plunger pump 625 includes a spring-biased pinchingmechanism 629. An actuator 634 applies a pumping force to force fluidinto the region of the tube 627 within the chamber 628 in the mannersimilar to the pump 600 of FIG. 141.

In stage 1, the valves 630, 631, and 632 are closed. The optical sensoror camera 626 estimates the volume within the region of the tube 627disposed within the chamber 628. The plunger 633 may compress the tube627 to determine if the plunger 633 moves beyond a predetermined amountto perform a check of the valves 630 and 631. That is, if the plunger633 moved beyond a threshold amount, a processor 37 may determine thatone of the valves 630 and 631 is leaking.

In stage 2, the valve 631 is opened, and fluid is forced into thechamber 628 by actuation of the plunger 633. In stage 3, another opticalvolume estimate is made after both valves 631 and 632 are closed. Instage 4, the valves 632 is opened. If an occlusion exists, thespring-biased pinching mechanism 629 cannot discharge all of the fluidout of the tube 627 within the chamber 628. If no occlusion exists, thenthe spring-biased pinching mechanism 629 can discharge the fluid out.During stage 5 a volume measurement is made to determine if the fluidhas been discharged beyond a threshold. If fluid has not been dischargedbeyond a threshold, the processor 37 of FIG. 3 determines that anocclusion exists

FIG. 145 shows a plunger pump 635 having a chamber 636 having an opticalsensor 637 to estimate fluid volume of a tube 638 having a spring-biasedpinch mechanism 639 around the tube 638 and a plunger 640 and pinchvalves 641, 642, and 643 in accordance with an embodiment of the presentdisclosure. The optical sensor 637 may be an LED time-of-flight deviceor a camera. The manner of operation of the plunger pump 635 may be thesame as the plunger pump 625 of FIG. 144.

FIG. 146 shows a plunger pump 644 having a chamber 645 with an opticalsensor 646 to estimate fluid volume of a tube 647 having a spring-biasedpinch mechanism 648 around the tube 647 and a plunger 649 and pinchvalves 650, 651, and 652 outside the chamber 645 in accordance with anembodiment of the present disclosure. The plunger pump 644 may operatein the same manner of operation of the pump 625 of FIG. 144.

FIG. 147 show several views of a plunger pump 653 having an AVS assembly655 with pinch valve disposed 656 and 657 within the variable volume 658of the AVS assembly 659, and a plunger 660 and pinch valve 661 disposedoutside the variable volume 658 in accordance with an embodiment of thepresent disclosure. Note that the pinch valves 656 and 657 whollytraverse through the variable volume 658. FIG. 148 shows an twocross-sectional views of the plunger pump of FIG. 147 in accordance withan embodiment of the present disclosure. FIG. 149 shows an alternativetwo cross-sectional views of the plunger pump of FIG. 147 in accordancewith an embodiment of the present disclosure. Note in the two views ofFIG. 148, the pinch valve is disposed around the tube and in FIG. 149the pinch valve is disposed on one side of the tube.

FIG. 150 illustrates the stages 1-4 during normal operation of a plungerpump 662 having a spring-biased plunger 663 in accordance with anembodiment of the present disclosure. In stage 1, the plunger 663 ispulled away from the tube 664 and the pinch valve 665 is opened. An AVSmeasurement is taken. In stage 2, the pinch valves 665 is closed and theplunger 663 compresses the tube 664. Another AVS measurement is taken.In stage 3, the pinch valve 666 is opened and the plunger 663 pushesfluid out of the tube 664. An AVS sweep is performed to estimate thevolume of fluid delivered. In some embodiments, the plunger 663 includesa linear hall effect sensor which correlates the movement of the plungerbetween stages 2 and 3 to estimate the amount of fluid discharged.

FIG. 151 illustrates the stages for detecting an occlusion for theplunger pump 622 of FIG. 150 in accordance with an embodiment of thepresent disclosure. Stage 3 compares the AVS measurements when anocclusion occurs vs. a normal fluid delivery. The processor 37 of FIG. 3can detect when not enough fluid is delivered thereby indicating to theprocessor than an occlusion has occurred.

FIG. 152 illustrates stages 1-2 for leakage detection for the plungerpump 622 of FIG. 150 in accordance with an embodiment of the presentdisclosure. In stage 1, the pinch valve 665 is opened and the plunger663 is opened thereby drawing fluid into the tube 664. In stage 2, afterthe pinch valve 665 is compressed against the tube 664, the plungerapplies a force against the tube 664. If one of the valves 665 and 666is leaking, in stage 2, the AVS measurement would indicate a leakage offluid (i.e., the variable volume would increase.

FIG. 153 illustrates the stages 1-2 for detecting a failed valve and/orbubble detection for the plunger pump 602 in accordance with anembodiment of the present disclosure. As shown in stage 2, if thevariable volume increases beyond a predetermined threshold and does notcontinue to decrease, the processor 37 of FIG. 3 may determine that abubble exists in the tube 664.

FIG. 154 illustrates the stages for empty reservoir detection and/orupstream occlusion detection for a plunger pump 662 in accordance withan embodiment of the present disclosure. As shown in stage 2, if the AVSsweeps indicate that fluid is not being drawn into the tube 664, thenthe processor 37 of FIG. 3 may determine that the upstream reservoir isempty.

FIG. 155 illustrates the stage for free flow prevention for a plungerpump 662 in accordance with an embodiment of the present disclosure.That is, when a free flow condition is detected, the plunger 663 maycompress against the tube 664 to stop the free flow.

FIG. 156 illustrates the stages for a negative pressure valve check forthe plunger pump 662 in accordance with an embodiment of the presentdisclosure. Stage 1, the plunger 663 is compressed against the tube 664,and both valves 665 and 665 are closed. In stage 2, the plunger 663 islifted from the tube 665. If there is a leak, the compliance of the tube664 will pull in fluid which is detected by the AVS sweeps. As shown inStage 3, the valves 665 and 665 are opened.

FIGS. 157-158 show views of a plunger pump 670 having a cam shaft 671that traverses the variable volume 672 of an AVS assembly 673 inaccordance with an embodiment of the present disclosure;

FIGS. 159-162 illustrate several cam profiles in accordance with severalembodiments of the present disclosure. The cam profiles of FIGS. 159-162may be used with the peristaltic pump 662 of FIGS. 150-158, or anysufficient pump disclosed herein.

FIG. 159 shows a cam profile that uses the integrity check described inFIGS. 150-158 except for a negative pressure valve check, and can beused for forward pumping and backward pumping. The backward pumping maybe used during an infiltration test as described herein. FIG. 160 showsa cam profile which uses the integrity checks described in FIGS. 150-158without the negative pressure check. Rotation of the cam in a back andforth manner causes fluid flow in the cam profile of FIG. 160 when thecam is rocked from 0 to 155 degrees. Back pumping is accomplished in thecam profile of FIG. 160 by rotating the cam shaft back and forth from315 degrees to 160 degrees. In FIG. 161 a cam profile is shown that usesthe integrity check described in FIGS. 150-158 except for a negativepressure valve check. The cam profile in FIG. 161 can be used to provideforward fluid flow of the pump. FIG. 161 shows a cam profile that pulsesfluid when rotated continuously in one direction with a zero total fluidflow. The chart in the bottom right hand corner of FIG. 162 shows themovement to achieve forward, backwards, and swishing fluid movement.

FIG. 163 illustrates a peristaltic pump 675 having a plunger 676 and apinch valve 677 outside of an AVS variable volume 678 with two pinchvalves 679 and 680 on the interface of the AVS variable volume 678 inaccordance with an embodiment of the present disclosure. FIG. 164illustrates stages 1-5 of operation of the peristaltic pump of FIG. 163(in simplified version) in accordance with an embodiment of the presentdisclosure.

FIG. 165 illustrates a peristaltic pump 681 having two plungers 682 and683 external to an AVS variable volume 684 in accordance with anembodiment of the present disclosure. FIG. 166 illustrates severalstages 1-6 of the peristaltic pump 681 of FIG. 165 in accordance with anembodiment of the present disclosure;

FIG. 167 illustrates a peristaltic pump 685 having a plunger 686 with alinear sensor 687 in accordance with an embodiment of the presentdisclosure. FIG. 168 illustrates a graphic of data from the linearsensor 687 of the peristaltic pump 685 of FIG. 167 in accordance with anembodiment of the present disclosure. As shown in FIG. 168, the amountof movement of the plunger 686 between the pressurized stage (e.g., bothpinch valves closed 688 and 689 and the plunger's 686 spring applying aforce again the tube 690) and the delivery stage (e.g., the outlet pinchvalve 689 is opened) is correlated with the amount of fluid discharged.The correlation between the amounts of fluid discharged with the deltaoutput from the sensor 687 may be determined empirically. The plunger686 may be spring loaded against the tube 690 such that the cam onlycomes into contact with a cam follower coupled to the plunger 686 inorder to lift the plunger 686 away from the tube 690.

FIG. 169 illustrates the stages of the peristaltic pump of FIG. 167 inaccordance with an embodiment of the present disclosure. FIG. 170illustrates the detection of an occlusion condition vis-à-vis anon-occluded condition in accordance with an embodiment of the presentdisclosure. That is, the plunger position data is shown for the normalvs. occluded conditions. Note that when there is an occlusion, fluiddoes not discharge and thus the plunger position does not move as much.This may be detected by the processor 37 of FIG. 3. FIG. 171 illustratesthe detection of a valve leak vis-à-vis a full-valve-sealing condition.FIG. 172 illustrates the detection of a too much air in the tube or avalve fail vis-à-vis a proper operation.

FIG. 173 shows a block diagram that illustrates the electronics of aperistaltic pump in accordance with another embodiment of the presentdisclosure. That is, FIG. 173 shows the electronics of one of pumps 16,17, and 18 of FIG. 1 in one specific embodiment. FIG. 174 shows a blockdiagram that illustrates the electronics of another embodiment of theperistaltic pump of one of the pumps 16, 17, and 18 in FIG. 1.

FIG. 175 shows a perspective view of peristaltic pump 700 in accordancewith an embodiment of the present disclosure. The peristaltic pumpincludes an AVS chamber (see the AVS chamber 714 of FIG. 184). Theperistaltic pump 700 includes cams 701, 702, and 703 that rotate alongwith a cam shaft 704 coupled to a motor via a gear 705. The cam 702control an inlet pinch valve, the cam 702 controls a plunger, and thecam 703 controls an outlet pinch valve.

The cams 701-703 may be shaped to provide a peristaltic-pumping actionalong the tube 707. The cams 701-703 may be shaped to provide a threestage pumping action or a four stage pumping action.

The three stage pumping action includes stages 1, 2, and 3. In stage 1,the outlet valve is closed, the inlet valve is opened, and the plungeris lifted off of the tube. In one embodiment, the outlet valve issubstantially closed before the inlet valve is substantially open. Instage 2, the inlet valve is closed, and the spring-biased plunger isallowed by the cam to apply a compression force against the tube 707. Instage 3, the outlet valve is opened such that the compressive force ofthe spring's plunger compresses out the fluid towards the patient. Alinear sensor (e.g., optical or hall-effect) measures the position ofthe plunger. A processor coupled to a motor to control the cam shaft 704and coupled to the linear sensor may compare the difference of theplunger's position in stage 2 when the plunger stops movement and fullycompresses against the tube 707 and at the end of stage 3 (all fluid hasbeen forced out towards the patient and the plunger stops moving becauseno additional fluid may be compressed out of the tube). In anotherembodiment, the processor, coupled to the processor coupled to a motorto control the cam shaft 704 and coupled to the linear sensor, maycompare the difference of the plunger's position in stage 2 when theplunger rate of movement drops below a defined threshold and duringstage 3 when the plunger rate of movement drops below a given thresholdor the plunger position drops below a defined value. The thresholds forthe rate of movement and position of the plunger are determined bycalibration experiments. The processor uses the measured differencesbetween the displacements between these two positions to correlate thedifference to a volume of fluid pumped (e.g., by comparing the deltavalue (the difference between the two measurements) to values in alook-up table). Optionally, in stage 3, the opening of the outlet valveis controlled by the rotation of the cam 704 to achieve a target fluiddischarge-rate profile, e.g., the delta is used between the measurementof stage 2 and in real-time as the outlet valve is opened in stage 3(e.g., the delta is continuously calculated).

During stage 2, if the plunger moves beyond a predetermined thresholdand/or beyond a predetermined slope, one of the inlet valve and theoutlet valve may be leaking. For example, if the plunger quickly movesto compress the tube and continues to move (e.g., beyond a predeterminedslope), the processor may determine that one of the inlet and outletvalves are leaking. The processor (the processor 37 of FIG. 3) iscoupled to the linear sensor may issue an alarm and/or alert.

During stage 2, if the plunger moves beyond a predetermined thresholdwhen the cams allows the compression of the spring to compress the tubeor the movement slows as the plunger hits the tube and then moves morebeyond a predetermined threshold (as the bubble is compressed), it mayindicate that a bubble exists within the tube. For example, if theplunger moves as the cam follower moves the spring-biased plungertowards the tube, then momentarily stops, and then moves again, theprocessor may determine that air within the tube has been compressed. Insome embodiments, movement beyond a predetermined threshold may suggestthat air exists within the tube. The processor coupled to the linearsensor may issue an alarm and/or alert. In some embodiments, todistinguish between a leaking valve and a bubble, a downstream bubblesensor (not shown) may be used by the processor to distinguish betweenthe two error conditions.

In some embodiments, if the spring-biased plunger in stage 2 movestowards the tube and does not engage the tube until after apredetermined threshold has been crossed, the processor may determinethat an upstream occlusion exists and the tube did not fill up withfluid during stage 1.

In some embodiments, if the spring-biased plunger in stage 3 does notmove beyond a predetermined threshold, the processor may determine thata downstream occlusion exists (e.g., the tube cannot discharge fluiddownstream). Additionally or alternatively, the processor may determinethat a downstream occlusion exists when each cycles of the stages 1-3,less and less fluid is discharged to a patient (i.e., the compliance isincreasing taking in fluid downstream).

In some embodiments of the present disclosure, the cams 701, 702, and703 may be shaped to have a four stage pumping action.

In stage 1, the outlet valve is closed, the inlet valve is opened, andthe plunger is lifted off of the tube. In stage 2, the inlet valve isclosed, and the spring-biased plunger is allowed by the cam to apply acompression force against the tube 707. In stage 3, the plunger islifted off of the tube and the outlet valve is opened. In stage 4, thecam 702 allows the plunger to apply the compressive force of thespring's plunger to compress out the fluid towards the patient. A linearsensor (e.g., optical or hall-effect) measures the position of theplunger. A processor coupled to a motor to control the cam shaft 704 andcoupled to the linear sensor may compare the difference of the plunger'sposition in stage 2 when the plunger stops movement and fully compressesagainst the tube 707 and at the end of stage 4 (all fluid has beenforced out towards the patient and the plunger stops moving because noadditional fluid may be compressed out of the tube). The processor usesthe measured differences between the displacements between these twopositions to correlate the difference to a volume of fluid pumped (e.g.,by comparing the delta value (the difference between the twomeasurements) to values in a look-up table). Optionally, in stage 4, themovement of the plunger to compress the tube using the plunger'scompressive force (as allowed by the cam 702) is controlled by therotation of the cam 704 to achieve a target fluid discharge-rateprofile, e.g., the delta is used between the measurement of stage 2 whenthe plunger fully compresses the tube and the movement of the plunger inreal-time as the plunger is allowed to compress the tube 707 (e.g., thedelta is continuously calculated).

In some embodiments, a downstream occluder may be adjusted to smooth theflowing of the fluid to the patient.

In some embodiments AVS may be used instead of the linear positionsensor. In some embodiments, only the linear position sensor is used. Inyet additional embodiments, both of the AVS and the linear positionsensor are used.

FIGS. 176-180 show data from several AVS sweeps in accordance with anembodiment of the present disclosure. The AVS sweeps of FIGS. 176-180are for the peristaltic pump 700 of FIG. 175.

FIG. 176 shows data, including a magnitude and phase response, of avariable volume around the tube 707 of the peristaltic pump 700 of FIG.175 relative to a reference volume. That is, the data as shown in FIG.176 is correlated to the volume of air around the tube 707 (see FIG.175) within an acoustically sealed region as shown in FIG. 184 (i.e., avariable volume chamber).

FIG. 177 illustrates several AVS sweeps performed using the peristalticpump 700 of FIG. 175. Note that, although the plunger is spring-loadedagainst the tube 707 in Sweep 3 and the outlet valve is opened by thecam 703, the fluid is not discharged downstream towards the patient. Theprocessor 37 of FIG. 3 may determine that a downstream occlusion existsin this circumstance.

FIG. 178 shows several AVS sweeps using the pump 700 of FIG. 175. Insweeps 2 and 3 of FIG. 178, the cam 702 allows the plunger's spring tocompress against the tube 707, but the cams 701 and 703 force the pinchvalves closed. In sweep 3, the inlet and outlet valves have remainedclosed, however, the variable volume is increasing which therebyindicates that the fluid is being discharged out of one of the inlet andoutlet valves. The processor 37 of FIG. 3 may determine that one of theinlet and outlet valves are leaking when the sweeps data appears as insweeps 2 and 3 despite that the inlet and outlet valves have remainedclosed.

FIG. 179 shows several AVS sweeps using the pump 700 of FIG. 175. Insweep 1, the cams 701 and 703 close the valves, and the cam 702 allowthe plunger's spring the compress against the tube 707. In sweep 2, thecams 701 and 703 have kept the valves closed, however, the plunger'sspring has moved the plunger beyond an predetermined amount. Theprocessor 37 may determine that the movement of the plunger is becauseair is within the tube under the plunger. A downstream air detector 24(see FIG. 1) may be used to distinguish between movements caused by thecompressibility of air when air is within the tube 707 below the plungervs. a leaking inlet or outlet pinch valve.

FIG. 180 illustrates the AVS sweep performed during multiple (fullcycles) of fluid discharge towards the patient using the pump 700 ofFIG. 175 when there is a downstream occlusion. That is, each sweep maybe performed after the plunger is expected to discharge fluid towardsthe patient. As shown in sweep 4, the pump 700 is not discharging thefluid. For example, the pump 700 may slowly fill the downstreamcompliance of the tube 707 until the tube can no longer expand, in whichcase, the pump 700 has difficultly pumping additional liquid downstreambecause the spring of the plunger cannot apply sufficient force to pumpadditional liquid downstream. The processor 37 (see FIG. 3) maydetermine that the decreased liquid delivery during each cycle of thepump 700 indicates that a downstream occlusion exists.

FIGS. 181-183 show several side views of a cam mechanism of theperistaltic pump of FIG. 175 in accordance with an embodiment of thepresent disclosure. FIG. 181 shows a side sectional-view of the plunger706. The movement of the plunger 706 and cam follower 709 is monitoredby an optical cam follower position sensor 711.

There are various devices that may be used to sense the position of thepump plunger 706 and pinch valves of the pump of FIG. 175. Theseinclude, but are not limited to one or more of the following:ultrasonic, optical (reflective, laser interferometer, camera, etc),linear caliper, magnetic, mechanical contact switch, infrared lightmeasurement, etc. In one embodiment, a small reflective optical sensorassembly (hereinafter “optical sensor”) that fits into the exemplaryembodiments of the peristaltic pump 175, as shown and described, forexample, herein, may be used. The optical sensor in the variousembodiments has a sensing range that accommodates the components forwhich the optical sensor may be sensing, e.g., in some embodiments, theplunger 706. In the exemplary embodiment any optical sensor may be used,including, but not limited to a Sharp GP2S60, manufactured by SharpElectronics Corporation, which is a US subsidiary of Sharp Corporationof Osaka, Japan.

In various embodiments, the pumping apparatus may be based on theprinciple of indirect compression of a flexible tube segment through theapplication of a restoring force against the tubing segment by aspring-based apparatus. As shown in FIG. 181, a cam lobe or element 702may be eccentrically disposed on a shaft 705 to cause cam follower 709to move in a reciprocating fashion as the cam element 702 rotates.Plunger spring 710 in this illustration is biased to urge a plunger 706to compress the flexible tube segment 707 situated within theperistaltic pump 700. Thus, in this arrangement, a spring constant maybe selected for spring 710 to cause the plunger to compress flexibletube segment 707 to the extent necessary to deform the wall of the tubesegment when liquid having a pre-selected range of viscosities ispresent within it, and for a pre-determined flow resistance of the fluidcolumn to the end of a catheter or cannula attached to the terminal endof the flexible tube. In this way, the distance and speed with whichplunger 706 moves to compress tubing segment 707 can provide informationabout the state of the tubing distal to tubing segment 707, such aswhether there is a complete or partial occlusion involving the tube oran attached catheter, or whether the catheter has been dislodged out ofa blood vessel or body cavity and into an extravascular tissue space.The movement of the spring or attached elements (such as the plunger)may be monitored by one or more sensors, the data being transmitted to acontroller (e.g., the processor 37 of FIG. 3) for analysis of the rateand pattern of movement as the tube segment is compressed. Examples ofsuitable sensors for this purpose may include, for example, Hall Effectsensors, potentiometers, or optical sensors including LED-based,laser-based or camera-based sensing systems that are capable oftransmitting data to a controller employing various forms ofpattern-recognition software.

The action of peristaltic pump 700 of FIG. 175 is illustrated in FIG.182. FIG. 182a shows the cam lobe or element 704 contacting cam follower709, compressing spring 710, and moving the plunger 706 away from tubesegment 707. FIG. 182b shows cam lobe 704 having rotated about cam shaft705 away from cam follower 709, allowing spring 710 to extend, and theplunger 706 to begin compressing tube segment 707. In FIG. 182c , camlobe 704 has rotated sufficiently to completely release cam follower 709to allow spring 710 to extend sufficiently to allow the plunger 706 tocompletely compress tube segment 707. Assuming that an inlet valveacting on tube segment 707 entering pump 700 is closed, and an outletvalve acting on tube segment 707 leaving pump 700 is open, a volume ofliquid within tube segment 707 will be propelled distally out of thetube segment 707. Although the side-view shown in FIG. 182 is of aplunger, the operation of the inlet and outlet valve may be similarand/or the same.

FIG. 183 illustrates a scenario in which the resistance to flow of theliquid column within tube segment 707 is increased beyond thepre-determined functional range of the spring selected for pump 700. Ascam lobe 704 moves from a spring compressing position in FIG. 183a to aspring de-compressing position in FIG. 183b , the spring force isinsufficient to compress tube segment 707 quickly, and may only be ableto compress tube segment 707 partially, as shown in FIG. 183c . The rateof movement and end position of a component the plunger-spring-camfollower assembly may be detected by one more sensors appropriate forthis task (e.g., camera-based sensor), which may, for example, bemounted near or adjacent to plunger 706. This information may betransmitted to a controller, which can be programmed to interpret thesignal pattern in light of stored data that has previously beendetermined empirically. The pattern of volume-change vs. time of acompressed tube segment such as that shown in FIG. 180 may in some casesmirror the pattern to be expected of movement vs. time when the relativeposition of a component of the plunger-spring-cam follower assembly istracked.

FIG. 184 shows a sectional view of the pinch valves 715 and 716 andplunger 718 of the peristaltic pump of FIG. 175 in accordance with anembodiment of the present disclosure. In various embodiments, the tubesegment within the pumping apparatus is held against an anvil plateduring compression by a plunger. The tube segment may be held inposition by being secured in a form-following raceway having sufficientspace to allow for the lateral displacement of the tube segment walls asit is being compressed. However, this may allow for some lateralmovement of the tube segment in an uncompressed state. FIG. 185 shows analternative arrangement in which the tube segment may be held inposition by flexible side arms or fingers that can elastically spreadapart to accommodate the spreading sides of the tube segment as it iscompressed. FIG. 185 shows a plunger comprising flexible side arms orfingers to grip a tube segment to keep it relatively immobilized in botha non-compressed and compressed state. In an uncompressed or ‘unpinched’state, the flexible fingers fit snugly against the sides of the tubesegment, preventing lateral movement of the tube within the pumpingapparatus. In a compressed or ‘pinched’ state, the flexible fingerselastically spread apart to accommodate the lateral displacement of thetube segment walls as it is compressed, maintaining the overall positionof the tube segment within the pumping apparatus.

FIG. 186 shows an embodiment of a cam mechanism of a peristaltic pump719 in accordance with an embodiment of the present disclosure. A cam720 controls a pinch valve 721. A Cam 722 controls plungers 723, 724,and 725. A cam 726 controls another pinch valve 727. A latchingmechanism (e.g., a magnetic latch) may prevent the plungers 723 and 725from moving to compress the tube 728 as shown in FIG. 187.

FIGS. 188, 189, and 190A show several views of a peristaltic pump 729 inaccordance with the present disclosure. The peristaltic pump 729includes a cam shaft 730 coupled to cams 731, 732, 733, and 734 thatengage the cam followers 735, 736, 737, and 738, respectively. The camfollower 735 is coupled to a first pinch valve 739, the cam followers736 and 737 are coupled to a plunger 740, and the cam follower 738 iscoupled to another pinch valve 741. As shown in FIGS. 190B-190C, theplunger 740 includes a pincher 744 that engages fingers 743 forming araceway.

FIGS. 191-195 show several views of a peristaltic pump 745 in accordancewith an additional embodiment of the present disclosure. The peristalticpump 745 of FIGS. 190-195 is similar to the peristaltic pump 729 ofFIGS. 188-190C, except that the peristaltic pump 745 of FIGS. 190-195includes a torque balancing cam 746 coupled to a cam follower 747 thatoperate together to smooth the rotational torque of the camshaft 748.

FIG. 196A illustrates the torque profile of a rotating cam shaft of theperistaltic pumps of FIGS. 188-190C and of FIGS. 191-195 in accordancewith an embodiment of the present disclosure. The torque profile 749shows the torque of the peristaltic pumps of FIGS. 188-190C. torque 750shows the torque produced by the torque balancing cam 746 of theperistaltic pump of FIGS. 191-195. The torque profile 751 shows theresulting net torque on the camshaft 748 caused by the smoothingoperation of the torque balancing cam 746 (also see FIG. 196B).

FIG. 197 illustrates a cam profile for several cams for a peristalticpump in accordance with an embodiment of the present disclosure. The camprofile describes the four stage pumping action described above. Thesolid lines describe the linear position of the cams. The dashed linesplot the position of the plunger and valves. The Pump cam and plungerposition over time are plotted in 1300. The inlet valve cam and inletvalve position are plotted in 1302. The outlet valve cam and outletvalve position are plotted in 1304. In stage 1, the outlet valve closesat 1306. The inlet valve opens at 1308. The plunger is lifted off thetube at 1310, which allows fluid to enter the tube under the plunger. Instage 2, the inlet valve closes at 1312, while the plunger remainslifted off the tube. In stage 3, the plunger is allowed to compress thetube. The position of the plunger 1314 departs from the cam position dueto the presence of fluid in the tube. The controller may execute anumber of diagnostic tests including but not limited to leak tests, airin the line, occlusions based on the measured position and movement ofthe plunger during stage 3. In stage 4, the outlet valve is opened at1316 first. After the outlet valve is opened, the plunger is allowed tocompress the tube forcing liquid out of the pump. The plunger force issupplied by springs acting on the plunger or springs acting on theplunger cam followers. The cam may be formed to limit the descent of theplunger during stage 4. The actual position of the plunger may befurther limited by the fluid flow out of the tube. The processor on thepump may actively control the plunger position by controlling the camrotation based on the measured location of the plunger. This closed loopcontrol of the motor may provide low flow rates (FIG. 198). In otherembodiments at higher flows, the cam and/or motor will be controlled inan open loop.

FIG. 198 shows various feedback modes of a peristaltic pump inaccordance with an embodiment of the present disclosure. In a closedloop mode, feedback from the AVS measurements and/or the linear sensoris used to control the speed of the camshaft. In open loop mode, thespeed of rotation is selected by reference to a lookup table in responseto a target fluid flow rate.

FIG. 199 shows a graph illustrating data of a linear sensor used toestimate fluid flow in accordance with an embodiment of the presentdisclosure; The delta value from the plateau 752 caused by both inletand outlet valves being closed in a peristaltic pump with the plungerfully compressing against a fluid filled tube and the plateau 753 causeafter the outlet valve is opened and all of the fluid is expelled out ofthe peristaltic pump and the plunger is fully compressing against thetube by the force from its spring.

FIGS. 200-206 show an alternate embodiment of a peristaltic pump 1200wherein a motor 1204 may drive a cam shaft 1206 via a gear train 1208.The cams may actuate one or more valves 1226, 1228 and a plunger 1222via levers that rotate about a common axis. The tube 1202 is held inplace by a door 1212. The peristaltic pump 1200 may include a receptaclefor a slide occluder 1200 and mechanisms that prevent a free-flowcondition on the tube during installation of the tube in the peristalticpump 1200.

The cam shaft 1206 may include several cams 1232A-E. The cams 1232A-Emay control the position of several items that may include but are notlimited to the following: inlet pinch valve 1224, plunger 1222, outletpinch valve 1226, and a torque balancer. The cams 1232A-E may becontacted by wheels 1214A-E on the cam followers 1216A-E. The camfollowers 1214A-E may include magnets 1218A-E. The position of eachmagnet may be detected by an array of sensors 1220. The pump controllermay calculate the position of a pump plunger 1222 and valves 1226, 1228from the sensor signals generated by the magnets 1218A-E. Theperistaltic pump 1200 may include an ultrasonic sensor 1228 to detectthe presence of the air bubbles in the fluid exiting the pump. Theultrasonic sensor 1228 may communicate with the pump controller.

The cam followers 1214A-E may have an L shape and may pivot about acentral axis at 1230. The cam followers are held against the cams1232A-E by springs 1234A-E. Spring 1234C may provide a torque balancingload. The springs 1234B and 1234D may provide the force to urge theplunger toward the anvil plate 1236. The springs 1234A and 1234E mayprovide the force to close the pinch valves 1226, 1228 against the anvilplate 1236.

FIG. 207 illustrates the installing tube with the slide occluder in theperistaltic pump 1200. In step 1, the door 1212 is open. In step 2, thetube 1202 and slide occluder 1210 are placed in position in theperistaltic pump 1200. In step 3, the slide occluder 1210 is slid intothe peristaltic pump 1200 and displaces slide 1242 and lever 1240 awayfrom the door and displaces button 1248 forward. The tube 1202 is heldnear the front peristaltic pump 1200 as the slide occluder 1210 so thatthe tube 1202 is in the narrow part of the slot and pinched closed. Instep 4 the door is closed. In step 5, the slide occluder 1210 pushed outby the movement of button 1248 toward the back of the peristaltic pump1200. The button 1248 moves lever 1240, which draws slide 1242 forward.The forward movement of the slide occluder 1210 releases the pinch onthe tube 1202 by the slide occluder 1202.

FIGS. 210-212 illustrate features to prevent the user from installing atube without the correct slide occluder. A tab 1250 prevents a slideoccluder 1210 from being installed that does not have a matching slot1252. A shutter 1254 prevents the door 1212 from closing. The shutter1254 is displaced by the slide occluder 1210 in step 3 of FIG. 207.

FIGS. 213-220 illustrate how the peristaltic pump 1200 prevents a freeflow condition when the tube 1202 is loaded and/or removed. The door1212 easily opens to an angular position 90° from the front of theperistaltic pump 1200. A small force may be applied to further rotatethe door 1212, which forces the plunger 1222 and the pinch valves 1224,1226 into the open position. The movement of the door 1212 pulls the Lshaped cam followers 1218A-E toward the front and thereby lifts theplunger 1222 and the pinch valves 1224, 1226 off the tube 1202.

FIG. 221 illustrates the ultrasonic air sensor 1228 that may detect airbubbles of a certain size in the fluid downstream of the pinch valve1266 pump. The pressure sensor 1260 may measure the static pressure inthe fluid downstream of the pump. The pressure sensor 1260 and airsensor 1228 may communicate with the pump controller.

FIG. 222-223 shows two views of a peristaltic pump 754 in accordancewith an embodiment of the present disclosure. The peristaltic pump 754includes a door lever 755 and a door 756. FIG. 224 shows the slideoccluder 757 in an open position against the tube 758. The slideoccluder 754 is carried in the slide occluder carriage 1312. The slideoccluder carriage 760 engages a pin 761 that is in mechanicalcommunication with the plunger lift lever 759 in FIG. 225. FIG. 225illustrates that as the door lever 755 is opened (see FIG. 244), aplunger lift lever 759 is not lifting the plunger 1310 and pinch valves.FIG. 226 shows how as the door lever 755 is opened, the carriage 760moves forward toward the door and moves the slide occluder 757 passedthe tube 758 so that the tube 758 is closed as it passes into the narrowsection of the slide occluder 757. At approximately the same time thatthe tube 758 is pinched closed by the slide occluder 757 the forwardmotion of the carriage 760 rotates the pin 761 which moves the plungerlift level 759 to lift the plungers 1310 and pinch valve off the tube758 as shown in FIG. 227. In FIG. 228, the door lever 755 is fullyopened and the carriage 760 stops moving. As shown in FIG. 229, theplunger lift lever 759 is in a stable over center position that willkeep the plunger 1310 off the tube 758 when the door lever 755 is fullyopened.

FIGS. 230-233 illustrate an interlock that may prevent the slideoccluder carriage 760 from moving and closing the plungers 1310 andvalves 1312 without the door 756 being closed first. FIG. 230 shows thedoor 756 open and the release tab 1316 exposed. The interlock pin 1318is shown in the interlocked position that prevents the slide occludercarriage 760 from moving. A spring 1320 pushes the interlock pin 1318toward the slid occluder carriage 760 and engages the interlock pin in amatching hole when the slide occluder carriage 760 is in position.

FIGS. 231-233 show the sequence of the door 756 opening and releasingthe interlock pin 1316 by withdrawing the release tab 1316. As the tabis withdrawn the interlock pin 1318 is pushed toward the slide occludercarriage 760.

FIG. 234 shows the door 756 open and the slide occluder 757 being liftedout of the slide occluder carriage 760. The tube 758 is in the narrowsection of the slide occluder 757 that pinches the tube 758 closed. FIG.235 illustrates placing the tube 758 into the pump between the anvilplate 1324 and the plunger 1310 and valves 1312. FIG. 236 shows theslide occluder 757 and tube 758 fully installed in the pump 754, wherethe slide occluder 757 is pinching the tube 758 closed. FIG. 237 showsthe door 756 and the door lever 755 being shut which slid the slideoccluder carriage 760 toward the rear of the pump 754. The movement ofthe slide occluder carriage 760 pushed the slide occluder 757 past thetube 758 so that the tube is open and rotated the pin 761 that in turnrotated the plunger lift lever 759 that released the plungers 1310 andvalves 1312 to descend and close the tube 758. FIG. 238 shows a frontview of the door 756 being shut.

FIGS. 239-245 show several views of the peristaltic pump of FIGS.222-238 in accordance with an embodiment of the present disclosure. Amotor 2001 rotates gears which in turn rotates a camshaft 772. As thecamshaft 772 rotates, the cams 2003, 2004, 2005, 2006, and 2007 rotatewith the camshaft 772. The cam 2003 engages a cam follower 769, whichpivots along a pivot 763 to move a pinch valve 770. The cams 2004 and2006 engage cam follows 766 and 765, which pivot along the pivot 763 tomove a plunger 767. The cam 2007 engages the cam follower 762 to movethe pinch valve 764. Additionally, the cam 2005 engages a cam follower768. The cam 2005 is shaped such that the engagement with the camfollower 768 at least partially balances the torque (e.g., to reduce thepeak toque). In some embodiments, the cam 2005 and the cam follower 768are optional. The inlet valve 770 (which is a pinch valve), the plunger767, and the outlet valve 764 (which is a pinch valve) may engage thetube 771 using the three or four stages of pumping action as describedabove. A bubble sensor 2008 may be used to distinguish between a bubbleand a leaking valve 764 or 770 (e.g., pinch valves) as described above.

The rotation of the cam shaft 772 may be controlled by the motor 2001such that while fluid is compressed by the plunger 767, the outlet valve764 is opened by a PID control loop to achieve a target discharge rateprofile (e.g., smoothed out discharge rate) as measured by the plungerposition sensor. In some embodiments, a range of angles only moves theoutlet valve (e.g., outlet pinch valve). In yet additional embodiments,in the four stage pumping action described above, the movement of theplunger 767 is closed after the outlet valve 764 opens to achieve atarget discharge rate profile (e.g., smoothed out discharge rate) asmeasured by the plunger's 767 position sensor.

As is easily seen in FIG. 241, the cams 2002, 2003, 2004, 2005, and 2006are shows as engaging the cam followers 769, 766, 768, 765, and 762,respectively. FIG. 242 shows a front view of the peristaltic pumpincluding the plunger 767, and the pinch valves 764 and 770 positionedto engage the tube 771.

A standard tubing pump 1000 with an optical monitoring system is shownin FIGS. 251 and 252. The optical monitoring system is comprised of acamera 1010 with a field of view that may include part or all of theplunger 1004, one pinch valve 1002, a portion of the tube 1006, fiducialmarks on the pinch valve 1014, fiducial marks on the plunger 1016,fiducial marks on the backstop 1018, a light source (not shown) and alight guide 1012 to illuminate the surfaces facing the camera 1010. Theoptical monitoring system may further additional cameras 1010 withfields of view that include or all of the plunger 1004, additional pinchvalves 1002, a portion of the tube 1006, fiducial marks on the pinchvalve 1014, fiducial marks on the plunger 1016, fiducial marks on thebackstop 1018, a light source (not shown) and a light guide 1012 toilluminate the surfaces facing the camera 1010. The optical monitoringsystem may further comprising one or more rear light sources 1102, rearlight guides 1104 and a transparent plunger 1006 to illuminate the backside of the tube 1006 relative to the camera 1010. The camera 1010 andlights may operate in a range of spectrums from ultraviolet to infrared.

The optical system may further be comprised of a processor, memory andsoftware that may allow the images to be interpreted to provide a rangeof information on the status of the pump, tubing and flow that includesbut is not limited to plunger position relative to the backstop 1005,the pinch valve position relative to the backstop 1005, the speed anddirection of the plunger 1004 and pinch valve 1002, the presence of thetube 1006, the presence of liquid or gas in the tube 1006, the presenceof gas bubbles in the tube 1006, the presence deformations in the tube1006. The processor may further interpret the information on plunger andvalve position to determine fluid flow rate, presence of an occlusion inthe line, presence of a leak in the tubing,

The optical monitoring system recognizes and measures the positions ofthe plunger 1004 and valves 1002 relative to the anvil plate 1005. Theanvil plate 1005 is the stationary part of the pump and elsewhere may bereferred to as the counter surface or occlusion bed. The pump controllermay command the optical monitoring system may take an image using thecamera 1010 and front or rear light sources. A processor located in thecamera or elsewhere may process the image using software to identify therelative distance and orientation of the plunger 1004 and valves 1002relative to the anvil plate 1005. In one embodiment, the machine visionsoftware may identify the elements 1002, 1004 and 1005 and theirlocation within its field of view through an edge detection algorithm asdescribed above. The detected edges may be e assigned to each element1002, 1004 and 1005 based the edge location within the field of view. Byway of an example, an edge detected in the up third of the field of viewmay be assigned as the anvil plate 1005, while an edge detected in thelower left quadrant may be assigned as the pinch valve 1002 if thecamera 1010 is the on the left hand side as shown in FIG. 251.

In another embodiment, the machine vision software may identify thepinch valve 1002, plunger 1004 and anvil plate 1005 and their locationwithin its field of view with fiducial marks located on each of theelements 1002, 1004 and 1005. Each element may include one or morefiducial marks that are located within the field of view of the camera1010. Fiducial marks will be assigned to each element 1002, 1004, 1005based on the region in the field of view that it is detected.Considering the left hand camera 1010 in FIG. 251 by way of example,fiducial marks in the lower left region may be assigned as the pinchvalve 1002, while fiducial marks in the lower right region may beassigned as the plunger 1004 and fiducial marks in the upper region maybe assigned to as the anvil plate 1005. A single fiducial mark may allowthe optical monitoring system to measure the relative movement of thepinch valve 1002, and plunger 1004 to the anvil plate 1006. More thanone fiducial mark on a single element may allow the optical monitoringsystem to identify elements that rotated in their plane of motion. Theprocessor may signal a warning or an alarm if one or more of theelements 1002, 1004 and/or 1005 have rotated beyond an allowed amount. Asignificant rotation may indicate a mechanical break in the pinch valve1002 or plunger 1004 or that the camera has rotated within its mountingon the camera door 1020.

The machine vision software may identify the fiducial elements bymatching a stored template to the image. The vision software may be anoff-the-shelf product such as Open Source Computer Vision referred to asOpenCV and available for download from the internet. The vision softwaremay use the function or module TemplateMatching to identify the fiducialmarks from a stored template.

The machine vision software may then calculate the relative position andorientation of elements 1002, 1004 and 1005 from observed locationwithin the camera's field of view and stored geometric data of the pinchvalve 1002, plunger 1004 and anvil plate 1005. The locations andorientations determined by the machine vision software may then bepassed to algorithms to identify specific conditions which include, butare not limited to the following: pinch valve opening, pinch valveclosing, plunger at maximum stroke, plunger at minimum stroke. Otheralgorithms may process the machine vision determined locations andorientation data to determine parameters that include but are notlimited to the following, plunger speed, fluid flow rate, occlusion inthe line, air in the line, external leaks. These conditions andparameters are determined in the same way as they are determined fromhall effect sensors measuring the location of the plunger 1004 and pinchvalves 1002, which is described above.

In other embodiments, the machine vision software may identify theconditions and determine the parameters described above. In otherembodiments, the relative position and orientation of the pinch valve1002, plunger 1004 and anvil plate 1006 may be calculated by algorithmsoutside the machine vision software.

The machine vision software or algorithms that process the output of themachine vision software may recognize a number of conditions includingbut not limited to the following: tubing is not present, tubing is notcorrectly placed, tubing is empty of fluid, tubing is full of fluid,tubing is deformed, and a gas bubble is present in the liquid.

The optical monitoring system may calculate the volume of the tube withfewer assumptions with data from an additional camera 1011 mounted at asubstantial angle to camera 1010 as shown in FIG. 252. The back light1102, light guide 1104 may supply infrared illumination to the back ofthe plunger 1004. The plunger 1004 may be nylon or similar material thatis transparent to infrared radiation. The plunger is uncoated in thefield of view of camera 1011 to provide a clear view of the tube throughthe plunger 1004 in the infrared spectrum. A machine vision softwarepackage may determine the profiles of the tube 1006 from camera 1010 andthe profile from camera 1011. An algorithm may calculate a firstthickness of the tube as seen by camera 1010 and a second distance asseen by camera 1011. The volume of the tube may then be calculated fromthe two distances and the known circumference of the tube. A comparisonof the two distances and the tube circumference may identify buckling inthe tube shape that would significantly change the volume of liquid inthe tube.

The volume of fluid in the tube 1006 may depend on the shape taken bythe filled-tube when the pinch valves 1002 are closed. The shape of thetube 1006 near the pinch valves 1002 may change after the pump iscalibrated due to a number of factors including but not limited tochanges in the tubing materials, changes in manufacturing, changes inhumidity and temperature. The camera 1010 may observe the shape of thetube 1006 near the pinch valve 1002. The tube may be illuminated withvisible or infrared light from the front or back. In a preferredembodiment, the tube may be illuminated from behind with infrared light.Here illuminating from behind refers to placing the source of theillumination on the opposite side of the tube 1006 from the camera 1010.

In one embodiment, the machine vision software may detect the tube shapeusing edge detection. An algorithm may compare the observed tube shapeto a shape stored in the memory. In one embodiment the algorithm maycorrect the volume of fluid per stroke to account for the changed tubeshape. In another embodiment, the algorithm evaluating the tube shapemay signal a warming or alarm to a higher level algorithm. In anotherembodiment, the machine vision software may confirm an acceptable tubeshape by attempting to match a template of the accepted tube shape tothe image. The machine vision software or the next higher level ofsoftware control may signal a warning or alarm if an acceptable tubeshape is not identified.

The cameras 1010, 1011 may include either CCD (charge coupled device) orCMOS (Complementary Metal Oxide Semiconductor) chips to convert lightinto electrical signals that can be processes to generate an image. Oneexample of a camera is HM0357-ATC-00MA31 by Himax Imaging, Inc. ofIrvine Calif. USA. The cameras 1010, 1011 and lights 1012 may be poweredon only when taking measurements in order to reduce power consumption.

The pinch valve 1002, plunger 1004, tube 1006 and anvil plate 1005 maybe illuminated from the front. Front illumination refers to a lightsource that is on the same side of the object of interest as the camera1010 and supplies illumination to the camera 1010 by reflection from theobject of interest. One embodiment to supply front illumination iscomprised of a light bar 1012 that transmits light from LED's mounted inthe camera door 1020. One embodiment of the light bar 1012 is shown inFIG. 253. Light is supplied to the end surfaces 1032 of the light barfrom LED's or other light sources mounted in the camera door 1020. Thefront surface 1030 and back surface (not shown) are covered with amaterial that reflects the supplied light. In one embodiment, the frontand back surfaces are covered with an aluminized tape. Holes 1036provide a clear field of view for the cameras 1010. The light bar mayinclude a surface around each hole 1036 that is roughened to provide adiffuse light that illuminates the front of the pinch valve 1002,plunger 1004, tube 1006 and anvil plate 1005. The area around the holes1036 may be recessed and then roughened to provide more diffuse light.

It may be advantageous to provide backlighting or illumination from theopposite side of the tube 1006 relative to the camera 1010. Backlightingmay allow clearer visualization of the tube shape and or the shape ofthe volume inside the tube 1006. One embodiment places the rear lightsource on the back of the pump 1000. The rear light source 1102 may bean LED or other light providing illumination in the ultraviolet, visibleand or infrared range. A light guide 1104 may direct the light to theback of the plunger 1004. The plunger may be made from a material thatis transparent to the spectrum of light emitted by the light source1102. In one embodiment, the plunger is made from nylon and the lightsource 1102 provides infrared illumination, which the camera 1010 cansense. In some embodiments, the backlight may be a plurality of lightsources. The plurality of light sources may be controlled and/ormodulated such that only specific lights are on that are necessary toilluminate a pixel being exposed. For example, the camera may have aregion of interest, and only the lights needed to illuminate the regionof interest are turned on during the exposure time of pixels within theregion of interest. In some embodiments, the lights may be rows and/orcolumns of lights and/or pixels of lights (e.g., an array of LEDlights).

The spectrum of the rear light source 1102 and camera 1010 may beselected to maximize the visibility of the fluid in the tube. In oneembodiment, the spectrum may be broad to provide the maximum light tovisualize the tube. In another embodiment, a set of filters in front ofthe rear light source 1102 emits a narrow range of the infrared spectrumthat passes through the light guide 1104, plunger 1004 and tube 1006,but is absorbed by the liquid in the tube. The light source 1102 mayalso emit a narrow range of the infrared spectrum that passes throughthe light guide 1104. In another embodiment, the filters to allow onlythe desired band of infrared are in front of the camera 1010.

Acoustic Volume Sensing

The follow discussion describes acoustic volume sensing that may beperformed by a processor disclosed herein with a speaker and twomicrophones (e.g., a reference microphone and a variable-volumemicrophone) of a peristaltic pump, e.g., a peristaltic pump disclosedherein; AVS may be used to estimate liquid within a reservoir disclosedherein, to estimate an amount of liquid discharged from a reservoirdisclosed herein, and/or to estimate a liquid discharge rate of areservoir disclosed herein. Table 1 shows the definition of variousterms as follows:

TABLE 1 Term Definition Symbols P Pressure p Pressure Perturbation VVolume v Volume Perturbation γ Specific Heat Ratio R Specific GasConstant ρ Density Z Impedance f Flow friction A Cross sectional Area LLength ω Frequency ζ Damping ratio α Volume Ratio Subscripts 0 SpeakerVolume 1 Reference Volume 2 Variable Volume k Speaker r Resonant Port zZero p Pole

The acoustic volume sensor (“AVS”) measures the fluid volume displacedby the non-liquid side of a reservoir in the AVS chamber, e.g., anacoustic housing or within a reservoir, etc. The sensor does notdirectly measure the fluid volume, but instead measures the variablevolume of air, V2, within the AVS chamber; if the total volume of AVSchamber remains constant, the change in the V2 will be the directopposite of the change in the fluid volume. The AVS chamber is thevolume of air in fluid communication with a variable-volume microphonebeyond the acoustic port.

The volume of air, V2, is measured using an acoustic resonance. Atime-varying pressure is established in the fixed volume of thereference chamber, V1, using a speaker. This pressure perturbationcauses cyclic airflow in the acoustic port connecting the two volumes,which in turn causes a pressure perturbation in the variable volume. Thesystem dynamics are similar to those of a Helmholtz oscillator; the twovolumes act together as a “spring” and the air in the port connectingthe volumes as a resonant mass. The natural frequency of this resonanceis a function of the port geometry, the speed of sound, and the variablevolume. The port geometry is fixed and the speed of sound can be foundby measuring the temperature; therefore, given these two parameters, thevariable volume can be found from the natural frequency. In someembodiments of the present disclosure, a temperature sensor is usedwithin the acoustic housing and/or within the non-liquid side of areservoir. In some embodiments, the temperature is considered to be apredetermined fixed value, e.g., is assumed to be room temperature, etc.

The natural frequency of the system is estimated by measuring therelative response of the pressures in the two volumes to differentfrequency perturbations created by the speaker. A typical AVSmeasurement will consist of taking an initial measurement. The liquid isthen released from the liquid side of one or more reservoirs anddelivered to the patient (after which a second volume measurement istaken). The difference between these measurements will be the volume ofliquid delivered to the patient. In some embodiments a measurement willbe taken before filling the liquid side of the one or more reservoirsand/or prior to discharging the liquid, e.g., when the syringe pump ispreloaded, to detect any failures of the fluidic system.

An AVS measurement may occur in accordance with the following acts: (1)the processor will turn on power to the AVS electronics, enable the ADCof the processor, and initialize an AVS algorithm; (2) an AVSmeasurement consists of collecting data at a number of differentfrequencies; (3) optionally measuring the temperature; and (4) thenrunning an estimation routine based on the collected data to estimatethe volume of liquid in the liquid side of a reservoir.

To collect data at each frequency, the speaker is driven sinusoidally atthe target frequency and measurements are taken from the two microphonesover an integer number of wavelengths, e.g., the reference microphoneand the variable volume microphone (as described above). Once the datahas been collected, the processor disclosed herein performs a discreteFourier transform algorithm on the data to turn the time-series datafrom the microphones into a single complex amplitude. Integrity checksare run on the data from the microphones to determine if the data isvalid, e.g., the response is within a predetermined phase and/oramplitude range of the acoustic frequency.

The frequency measurements are taken at a number of differentfrequencies. This sine-sweep is then used by the estimation routine toestimate the variable volume. After the estimation is complete, otherintegrity checks is may be performed on the whole sine sweep, includinga secondary check by a processor disclosed herein.

In some embodiments, after the a processor disclosed herein verifies themeasurement integrity, the volume estimates are finalized and the sensoris powered off.

AVS Resonance Model

The governing equations for the AVS system can be found fromfirst-principles given a few simplifying assumptions. The system ismodeled as two linearized acoustic volumes connected by an idealizedacoustic port.

Modeling the Acoustic Volumes

The pressure and volume of an ideal adiabatic gas can be related byEquation (35) as follows:

PV ^(γ) =K  (35),

where K is a constant defined by the initial conditions of the system.Equation 1 can be written in terms of a mean pressure, P, and volume, V,and a small time-dependent perturbation on top of those pressures, p(t),v(t) as illustrated in Equation (36) as follows:

(P+p(t))(V+v(t))^(γ) =K  (36).

Differentiating Equation (36) results in Equation (37) as follows:

{dot over (p)}(t)(V+v(t))^(γ)+β(V+v(t))^(γ−1)(P+p(t)){dot over(v)}(t)=0  (37)

Equation (37) simplifies to Equation (38) as follows:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\gamma \; \frac{P + {p(t)}}{V + {v(t)}}{\overset{.}{v}(t)}}} = 0.} & (38)\end{matrix}$

If the acoustic pressure levels are much less than the ambient pressurethe Equation (38) can be further simplified to Equation (39) as follows:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\frac{\gamma \; P}{V}{\overset{.}{v}(t)}}} = 0.} & (39)\end{matrix}$

Using the adiabatic relation, Equation (40) can be shown as follows:

$\begin{matrix}{\frac{P}{V} = {\left( \frac{P + {p(t)}}{V + {v(t)}} \right){\left( \frac{P + {p(t)}}{P} \right)^{- \frac{\gamma + 1}{\gamma}}.}}} & (40)\end{matrix}$

Thus, the error assumption is shown in Equation 41 as follows:

$\begin{matrix}{{error} = {1 - {\left( \frac{P + {p(t)}}{P} \right)^{- \frac{\gamma + 1}{\gamma}}.}}} & (41)\end{matrix}$

A very loud acoustic signal (e.g., 120 dB) would correspond to pressuresine wave with amplitude of roughly 20 Pascal. Assuming air atatmospheric conditions has the parameters of γ=1.4 and P=101325 Pa, theresulting error is 0.03%. The conversion from dB to Pa is shown inEquation (42) as follows:

$\begin{matrix}{{\lambda = {{20{\log_{10}\left( \frac{p_{rms}}{p_{ref}} \right)}\mspace{14mu} {or}\mspace{14mu} p_{rms}} = {p_{ref}10^{\frac{\lambda}{20}}}}},} & (42)\end{matrix}$

where p_(ref)=20·μPa.

Applying the ideal gas law, P=ρRT, and substituting in for pressuregives the result as shown in Equation (43) as follows:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\frac{\gamma \; {RT}\; \rho}{V}{\overset{.}{v}(t)}}} = 0.} & (43)\end{matrix}$

This can be written in terms of the speed of sound in Equation (44) asfollows:

a=√{square root over (βRT)}  (44).

And, substituting in Equation (44) in Equation (43) results in Equation(45) as follows:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\frac{\; {\rho \; a^{2}}}{V}{\overset{.}{v}(t)}}} = 0.} & (45)\end{matrix}$

Acoustic impedance for a volume is defined in Equation 46 as follows:

$\begin{matrix}{Z_{v} = {\frac{p(t)}{\overset{.}{v}(t)} = {- {\frac{1}{\left( \frac{V}{\rho \; a^{2}} \right)s}.}}}} & (46)\end{matrix}$

Modeling the Acoustic Port

The acoustic port is modeled assuming that all of the fluid in the portessentially moves as a rigid cylinder reciprocating in the axialdirection. All of the fluid in the channel is assumed to travel at thesame velocity, the channel is assumed to be of constant cross section,and the end effects resulting from the fluid entering and leaving thechannel are neglected.

If we assume laminar flow friction of the form ΔP=fρ{dot over (v)}, thefriction force acting on the mass of fluid in the channel can bewritten: F=fρA²{dot over (x)}. A second order differential equation canthen be written for the dynamics of the fluid in the channel as shown inEquation (47) as follows:

μLA{umlaut over (x)}=ΔpA−fρA ² {umlaut over (x)}  (47),

or, in terms of volume flow rate as shown in Equation (48) as follows:

$\begin{matrix}{\overset{¨}{v} = {{{- \frac{fA}{L}}\overset{.}{v}} + {\Delta \; p\; {\frac{A}{\rho \; L}.}}}} & (48)\end{matrix}$

The acoustic impedance of the channel can then be written as shown inEquation (49):

$\begin{matrix}{Z_{p} = {\frac{\Delta \; p}{\overset{.}{v}} = {\frac{\rho \; L}{A}{\left( {s + \frac{fA}{L}} \right).}}}} & (49)\end{matrix}$

System Transfer Functions

Using the volume and port dynamics define above, the AVS system can bedescribed by the following system of Equations 50-53:

$\begin{matrix}{{{{\overset{.}{p}}_{0} - {\frac{\rho \; a^{2}}{V_{0}}{\overset{.}{v}}_{k}}} = 0},} & (50) \\{{{{\overset{.}{p}}_{1} + {\frac{\rho \; a^{2}}{V_{1}}\left( {{\overset{.}{v}}_{k} - {\overset{.}{v}}_{r}} \right)}} = 0},} & (51) \\{{{{\overset{.}{p}}_{2} + {\frac{\rho \; a^{2}}{V_{2}}{\overset{.}{v}}_{r}}} = 0},{and}} & (52) \\{{\overset{¨}{v}}_{r} = {{{- \frac{fA}{L}}{\overset{.}{v}}_{r}} + {\frac{A}{\rho \; L}{\left( {p_{2} - p_{1}} \right).}}}} & (53)\end{matrix}$

One equation can be eliminated if p₀ is treated as the inputsubstituting in

${\overset{.}{v}}_{k} = {\frac{V_{0}}{\rho \; a^{2}}{\overset{.}{p}}_{0}}$

as shown in Equations 54-56:

$\begin{matrix}{{{{\overset{.}{p}}_{1} + {\frac{V_{0}}{V_{1}}{\overset{.}{p}}_{0}} - {\frac{\rho \; a^{2}}{V_{1}}{\overset{.}{v}}_{r}}} = 0},} & (54) \\{{{{\overset{.}{p}}_{2} + {\frac{\rho \; a^{2}}{V_{2}}{\overset{.}{v}}_{r}}} = 0},{and}} & (55) \\{{\overset{¨}{v}}_{r} = {{{- \frac{fA}{L}}{\overset{.}{v}}_{r}} + {\frac{A}{\rho \; L}p_{2}} - {\frac{A}{\rho \; L}{p_{1}.}}}} & (56)\end{matrix}$

The relationship between the two volumes on each side of the acousticport is referred to as the Cross Port transfer function. Thisrelationship is illustrated in Equation (57) as follows:

$\begin{matrix}{{\frac{p_{2}}{p_{1}} = \frac{\omega_{n}^{2}}{s^{2} + {2{\zeta\omega}_{n}s} + \omega_{n}^{2}}},} & (57)\end{matrix}$

where

$\omega_{n}^{2} = {{\frac{a^{2}A}{L}\frac{1}{V_{2}}\mspace{14mu} {and}\mspace{14mu} \zeta} = {\frac{fA}{2L\; \omega_{n}}.}}$

This relationship has the advantage that the poles are only dependent onthe variable volume and not on the reference volume. Note that theresonant peak is actually due to the inversion of the zero in theresponse of the reference volume pressure. This means that that pressuremeasurement in the reference chamber will have a low amplitude in thevicinity of the resonance which may influence the noise in themeasurement.

Resonance Q Factor and Peak Response

The quality of the resonance is the ratio of the energy stored to thepower loss multiplied by the resonant frequency. For a pure second-ordersystem the quality factor can be expressed as a function of the dampingratio illustrated in Equation (58):

$\begin{matrix}{Q = {\frac{1}{2\zeta}.}} & (58)\end{matrix}$

The ratio of the peak response to the low-frequency response can also bewritten as a function of the damping ratio shown in Equation (59):

$\begin{matrix}{{G}_{\omega_{d}} = {\frac{1}{\zeta \sqrt{5 - {4\zeta}}}.}} & (60)\end{matrix}$

This will occur at the damped natural frequency ω_(d)=ω_(n)√{square rootover (1−ζ)}.

Electrical and Mechanical Analogies

The acoustic resonator is analogous to either a spring-mass-dampersystem or a LRC circuit, e.g., a resistor, inductor and capacitorcoupled together in series, for example.

Computing the Complex Response

To implement AVS, the system must get the relative response of the twomicrophones to the acoustic wave set up by the speaker. This isaccomplished by driving the speaker with a sinusoidal output at a knownfrequency; the complex response of each microphone is then found at thatdriving frequency. Finally, the relative responses of the twomicrophones are found and corrected for alternating sampling of theanalog-to-digital converter coupled to the a processor disclosed herein.

In addition, the total signal variance is computed and compared to thevariance of pure tone extracted using the discrete Fourier transform(“DFT”). This gives a measure of how much of the signal power comes fromnoise sources or distortion. In some embodiments of the presentdisclosure, this value can be used to reject and repeat badmeasurements.

Computing the Discrete Fourier Transform

The signal from each microphone is sampled synchronously with the outputto the speaker such that a fixed number of points, N, are taken perwavelength. The measured signal at each point in the wavelength issummed over an integer number of wavelengths, M, and stored in an arrayx by an interrupt service routine (“ISR”) in the processor disclosedherein after all the data for that frequency has been collected.

A discrete Fourier transform is done on the data at the integer valuecorresponding to the driven frequency of the speaker. The generalexpression for the first harmonic of a DFT is as follows in Equation(61):

$\begin{matrix}{x_{k} = {\frac{2}{MN}{\sum\limits_{n = 0}^{N - 1}{x_{n}{e^{{- \frac{2\pi \; i}{N}}{kn}}.}}}}} & (61)\end{matrix}$

The product MN is the total number of points and the factor of 2 isadded such that the resulting real and imaginary portions of the answermatch the amplitude of the sine wave illustrated in Equation (62):

$\begin{matrix}{x_{n} = {{{{re}\left( x_{k} \right)}{\cos \left( {\frac{2\pi}{N}{kn}} \right)}} + {{{im}\left( x_{k} \right)}{{\sin \left( {\frac{2\pi}{N}{kn}} \right)}.}}}} & (62)\end{matrix}$

This real part of this expression is illustrated in Equation (63):

$\begin{matrix}{{{re}(x)} = {\frac{2}{MN}{\sum\limits_{n = 0}^{N - 1}{x_{n}{{\cos \left( {\frac{2\pi}{N}n} \right)}.}}}}} & (63)\end{matrix}$

We can take advantage of the symmetry of the cosine function to reducethe number of computations needed to compute the DFT. The expressionabove is equivalent to Equation (64) as follows:

$\begin{matrix}{{{re}(x)} = {{\frac{2}{MN}\left\lbrack {\left( {x_{0} - x_{\frac{1}{2}N}} \right) + {\sum\limits_{n = 1}^{{\frac{1}{4}N} - 1}{{\sin \left( {\frac{\pi}{2} - {\frac{2\pi}{N}n}} \right)}\left\lbrack {\left( {x_{n} - x_{{\frac{1}{2}N} + n}} \right) - \left( {x_{{\frac{1}{2}N} - n} - x_{N - n}} \right)} \right\rbrack}}} \right\rbrack}.}} & (64)\end{matrix}$

Similarly, the imaginary portion of the equation is illustrated inEquation (65) as follows:

$\begin{matrix}{{{{im}(x)} = {{- \frac{2}{MN}}{\sum\limits_{n = 0}^{N - 1}{x_{n}{\sin \left( {\frac{2\pi}{N}n} \right)}}}}},} & (65)\end{matrix}$

which may be expressed as Equation (66):

$\begin{matrix}{{{im}(x)} = {- {{\frac{2}{MN}\left\lbrack {\left( {x_{\frac{1}{4}N} - x_{\frac{3}{4}N}} \right) + {\sum\limits_{n = 1}^{{\frac{1}{4}N} - 1}{{\sin \left( {\frac{2\pi}{N}n} \right)}\left\lbrack {\left( {x_{n} - x_{{\frac{1}{2}N} + n}} \right) + \left( {x_{{\frac{1}{2}N} - n} - x_{N - n}} \right)} \right\rbrack}}} \right\rbrack}.}}} & (66)\end{matrix}$

The variance of the signal at that driven frequency is illustrated inEquation (67) as follows:

$\begin{matrix}{\sigma_{tone}^{2} = {\frac{1}{2}{\left( {{{re}(x)}^{2} + {{im}(x)}^{2}} \right).}}} & (67)\end{matrix}$

The tone variance is proportional to the acoustic power at the drivenfrequency. The maximum possible value of the real and imaginary portionsof x is 2¹¹; this corresponds to half the A/D range. The maximum valueof the tone variance is 2²¹; half the square of the AD range.

Computing the Total Signal Variance

A good measure of the integrity of a measurement is the ratio of theacoustic power at the driven frequency relative to the total acousticpower at all frequencies. The total signal variance is given by theexpression in Equation (68):

$\begin{matrix}{\sigma_{total}^{2} = {{{\frac{1}{NM}{\sum\limits_{n = 0}^{{MN} - 1}p_{n}^{2}}} - {\overset{\_}{p}}^{2}} = {{\frac{1}{NM}{\sum\limits_{n = 0}^{{MN} - 1}p_{n}^{2}}} - {\left( {\frac{1}{NM}{\sum\limits_{n = 0}^{{MN} - 1}p_{n}}} \right)^{2}.}}}} & (68)\end{matrix}$

However, in some specific embodiments, the summations are performed inthe A/D interrupt service routine (ISR) where there are time constraintsand/or all of the microphone data must be stored for post-processing. Insome embodiments, to increase efficiency, a pseudo-variance iscalculated based on a single averaged wavelength. The pseudo-variance ofthe signal is calculated using the following relation illustrated inEquation (69) as follows:

$\begin{matrix}{\sigma_{total}^{2} = {{\frac{1}{{NM}^{2}}{\sum\limits_{n = 0}^{N - 1}x_{n}^{2}}} - {\frac{1}{N^{2}M^{2}}{\left( {\sum\limits_{n = 0}^{N - 1}x_{n}} \right)^{2}.}}}} & (69)\end{matrix}$

The result is in the units of AD counts squared. The summation will beon the order of

${\sum\limits_{n = 0}^{N - 1}x_{n}^{2}} = {O\left( {{NM}^{2}2^{24}} \right)}$

for a 12-bit ADC. If N<2⁷=128 and M<2⁶=⁶⁴ then the summation will beless than 2⁴³ and can be stored in a 64-bit integer. The maximumpossible value of the variance would result if the ADC oscillatedbetween a value of 0 and 2¹² on each consecutive sample. This wouldresult in a peak variance of

${\frac{1}{4}\left( 2^{12} \right)^{2}} = 2^{22}$

so the result can be stored at a maximum of a Q9 resolution in a signed32-bit integer.

Computing the Relative Microphone Response

The relative response of the two microphones, G, is then computed fromthe complex response of the individual microphones illustrated inEquations 70-72:

$\begin{matrix}{G = {\frac{x_{var}}{x_{ref}} = {\frac{x_{var}}{x_{ref}}{\frac{x_{ref}^{*}}{x_{ref}^{*}}.}}}} & (70) \\{{{Re}(G)} = {\frac{{{{Re}\left( x_{var} \right)}{{Re}\left( x_{ref} \right)}} + {{{Im}\left( x_{var} \right)}{{Im}\left( x_{ref} \right)}}}{{{Re}\left( x_{ref} \right)}^{2} + {{Im}\left( x_{ref} \right)}^{2}}.}} & (71) \\{{{Im}(G)} = {\frac{{{{Re}\left( x_{ref} \right)}{{Im}\left( x_{var} \right)}} - {{{Re}\left( x_{var} \right)}{{Im}\left( x_{ref} \right)}}}{{{Re}\left( x_{ref} \right)}^{2} + {{Im}\left( x_{ref} \right)}^{2}}.}} & (72)\end{matrix}$

The denominator of either expression can be expressed in terms of thereference tone variance computed in the previous section, illustrated asfollows in Equation 73:

Re(x _(ref))² +IM(x _(ref))²=2σ_(ref) ²  (73).

Correcting for A/D Skew

The speaker output may be updated at a fixed 32 times per sample. Forexample, as the driving frequency is changed, the speaker outputfrequency is also updated to maintain the fixed 32 cycles. The twomicrophones are sampled synchronous with the speaker output so thesampling frequency remains at a fixed interval of the driving frequency.The microphone A/D measurements, however, are not sampledsimultaneously; the A/D ISR alternates between the two microphones,taking a total of N samples per wavelength for each microphone. Theresult will be a phase offset between the two microphones of

$\frac{\pi}{N}.$

To correct for this phase offset, a complex rotation is applied to therelative frequency response computed in the previous section.

To rotate a complex number an angle

$\frac{\pi}{N}$

it is multiplied by

$e^{i\frac{\pi}{N}} = {{\cos \left( \frac{\pi}{N} \right)} + {i\; {{\sin \left( \frac{\pi}{N} \right)}.}}}$

The result is illustrated in Equation (74) as follows:

$G_{rotated} = {\left( {{{{Re}(G)}{\cos \left( \frac{\pi}{N} \right)}} - {{{Im}(G)}{\sin \left( \frac{\pi}{N} \right)}}} \right) + {\left( {{{{Im}(G)}{\cos \left( \frac{\pi}{N} \right)}} + {{{Re}(G)}{\sin \left( \frac{\pi}{N} \right)}}} \right)i}}$

Time Delays

In some embodiments, one of the assumptions when deriving the AVSequations is that the pressure is uniform in the acoustic volumes. Thisassumption is true if the acoustic wavelength is large compared to thedimensions of the AVS chamber. The wavelength of a sound wave at a givenfrequency can be computed with the following Equation (75):

$\begin{matrix}{\lambda = {\frac{a}{f}.}} & (75)\end{matrix}$

For example, the wavelength at 1 kHz is roughly 246 mm and at 5 kHz isroughly 49.2 mm. The AVS chamber may have a diameter such that the timedelay associated with acoustic waves traveling through the volumes has asmall but measurable effect. The effect can be modeled as a time delay(or time advance, depending on microphone orientation). The Laplacetransform of a pure time delay, d, is illustrated in Equation (76) asfollows:

G=e ^(ds)  (76).

The phase is influenced by the time delay, but not the magnitude ofsystem response. To correct for the time delays, the frequency responsedata may be corrected in advance by applying a model fit algorithm. Thecomplex amplitude may be rotated as a function of frequency accordingthe time delay equation above. The time delay may be assumed to befixed, so the rotation is only a function of frequency.

The time delay may be determined by running an optimization routine tofind the time delay to minimize the model fit error. Additionally oralternatively, there may be an apparent “time advance” in the data. Forexample, the reference microphone may experience a pressure perturbationslightly in advance of the acoustic port and the variable microphone mayexperience a pressure perturbation slightly behind the acoustic port.These “advances” and “delays” may be the effects of the propagation ofthe pressure waves and are in addition to “resonant” dynamics of thesystem, e.g., these effects may be accounted for.

Amplitude Leveling

The amplitude of the pressure measurements for a given speaker drivesignal may vary from device-to-device and also as a function of thedriven frequency. The device-to-device variations result frompart-to-part differences in microphone and speaker sensitivities (e.g.,roughly on the order of +/−3 dB). The frequency-based dependenciesresult from variations in speaker sensitivity over frequency as well asfrom the expected dynamics of the acoustic resonance.

To compensate, in some embodiments, the speaker gain is automaticallytuned during the AVS measurement. The speaker gains are stored in anarray with one entry for each of the sine-sweep frequencies, e.g.,within the memory 22 of FIG. 2. The amplitude of the microphone signal(from either the variable or reference microphone) may be checkedagainst the target amplitude. If it is either too large or too small abinary search routine may be employed to update the speaker gain at thatfrequency.

Checking Individual Measurement Integrity

It is possible for component errors, failures, or external disturbancesto result in an erroneous measurement. Component failures might includea distorted speaker output or failed microphone. External disturbancesmight include mechanical shock to the pump housing or an extremely loudexternal noise. These types of failures can be detected using twodifferent integrity checks: microphone saturation and out-of-bandvariance.

The microphone saturation check looks at the maximum and minimum valuesof the wavelength averaged signal for each microphone. If these valuesare close to the limits of the A/D then a flag within the processordisclosed herein is set indicating that the measurement amplitude wasout of range.

The out-of-band variance check compares the tone variance to the totalsignal variance for each microphone. In the ideal case the ratio ofthese signals will be 1—all of the acoustic power will be at the drivenfrequency. In the event of shock or an extremely loud external acousticnoise, more power will be present at other frequencies and this valuewill be lower than unity. In some embodiments, normal operation may beconsidered to have a ratio greater than 0.99.

In some embodiments, if an individual data point fails either of theseintegrity checks, it may be repeated or excluded without having torepeat the entire sine-sweep to help facilitate AVS robustness. Otherintegrity checks may be done based on the complete sine-sweep and aredescribed later.

Volume Estimation Using Swept Sine-Generalized Solution

The resonant frequency of the system may be estimated using swept-sinesystem identification. In this method the response of the system to asinusoidal pressure variation may be found at a number of differentfrequencies. This frequency response data may be then used to estimatethe system transfer function using linear regression.

The transfer function for the system can be expressed as a rationalfunction of s. The general case is expressed below for a transferfunction with an n^(th) order numerator and an m^(th) order denominator.N and D are the coefficients for the numerator and denominatorrespectively. The equation has been normalized such that the leadingcoefficient in the denominator is 1, as illustrated in Equations (77)and (78):

$\begin{matrix}{{G(s)} = \frac{{N_{n}s^{n}} + {N_{n - 1}s^{n - 1}} + \ldots + N_{0}}{s^{m} + {D_{m - 1}s^{m - 1}} + {D_{m - 2}s^{m - 2}} + \ldots + D_{0}}} & (77) \\{or} & \; \\{{G(s)} = {\frac{\sum\limits_{k = 0}^{n}{N_{k}s^{k}}}{s^{m} + {\sum\limits_{k = 0}^{m - 1}{D_{k}s^{k}}}}.}} & (78)\end{matrix}$

This equation can be re-written in the form of Equation 79 as follows:

$\begin{matrix}{{Gs}^{m} = {{\sum\limits_{k = 0}^{n}{N_{k}s^{k}}} - {G{\sum\limits_{k = 0}^{m - 1}{D_{k}{s^{k}.}}}}}} & (79)\end{matrix}$

Equation (80) shows this summation in matrix notation:

$\begin{matrix}{\begin{bmatrix}{G_{1}s_{1}^{m}} \\\vdots \\{G_{k}s_{k}^{m}}\end{bmatrix} = {{\begin{bmatrix}s_{1}^{n} & \ldots & s_{1}^{0} & {{- G_{1}}s_{1}^{m - 1}} & \ldots & {{- G_{1}}s_{1}^{0}} \\\vdots & \; & \vdots & \vdots & \; & \vdots \\s_{k}^{n} & \ldots & s_{k}^{0} & {{- G_{k}}s_{k}^{m - 1}} & \ldots & {{- G_{k}}s_{k}^{0}}\end{bmatrix}\begin{bmatrix}N_{n} \\\vdots \\N_{0} \\D_{m - 1} \\\vdots \\D_{0}\end{bmatrix}}.}} & (80)\end{matrix}$

Where k is the number of data points collected in the swept sine. Tosimplify the notation this equation can be summarized using the vectorsy illustrated in Equation (81).

y=Xc  (81).

Where y is k by 1, x is k by (m+n−1) and c is (m+n−1) by 1. Thecoefficients can then be found using a least square approach. The errorfunction can be written as shown in Equation (82):

e=y−Xc  (82).

The function to be minimized is the weighted square of the errorfunction; W is a k×k diagonal matrix, as illustrated in Equations 83-84.

e ^(T) We=(y−Xc)^(T) W(y−Xc)  (83).

e ^(T) We=y ^(T) Wy−(y ^(T) WXc)^(T) −y ^(T) WXc+c ^(T) x ^(T)WXc  (84).

The center two terms are scalars so the transpose can be neglected, asillustrated in Equations 85-87:

$\begin{matrix}{{{e^{T}{We}} = {{y^{T}{Wy}} - {2y^{T}{WXc}} + {c^{T}x^{T}{WXc}}}},} & (85) \\{{\frac{{\partial e^{T}}{We}}{\partial c} = {{{{- 2}X^{T}{Wy}} + {2X^{T}{WXc}}} = 0}},{and}} & (86) \\{c = {\left( {X^{T}{WX}} \right)^{- 1}X^{T}{{Wy}.}}} & (87)\end{matrix}$

In some embodiments, the complex transpose in all of these cases isutilized. This approach can result in complex coefficients, but theprocess can be modified to ensure that all the coefficients are real.The least-square minimization can be modified to give only realcoefficients if the error function is changed to Equation (88).

e ^(T) We=Re(y−Xc)^(T) WRe(y−Xc)+Im(y−Xc)^(T) WIm(y−Xc)  (88).

Then the coefficients can be found with the Equation (89):

c=(Re(X)^(T) WRe(X)+Im(X)^(T) WIm(X))⁻¹(Re(X)^(T) WRe(y)+Im(X)^(T)WIm(y))  (89).

Volume Estimation Using Swept Sine-Solution for a 2^(nd) Order System

For a system with 0^(th) order numerator and a second order denominatoras shown in the transfer function illustrated in Equation (90).

$\begin{matrix}{{G(s)} = {\frac{N_{0}}{s^{2} + {D_{1}s} + D_{0}}.}} & (91)\end{matrix}$

The coefficients in this transfer function can be found based on theexpression found in the previous section as follows Equation (92):

c=(Re(X)^(T) WRe(X)+Im(X)^(T) WIm(X))⁻¹(Re(X)^(T) WRe(y)+Im(X)^(T)WIm(y))  (92).

Where Equation (93) is as follows:

$\begin{matrix}{{y = \begin{bmatrix}{G_{1}s_{1}^{2}} \\\vdots \\{G_{k}s_{k}^{2}}\end{bmatrix}},{X = \begin{bmatrix}1 & {{- G_{1}}s_{1}} & {- G_{1}} \\\vdots & \vdots & \vdots \\1 & {{- G_{k}}s_{k}} & {- G_{k}}\end{bmatrix}},{{{and}\mspace{14mu} c} = {\begin{bmatrix}N_{0} \\D_{1} \\D_{0}\end{bmatrix}.}}} & (93)\end{matrix}$

To simplify the algorithm we can combine some of terms as illustrated inEquations 94-96:

c=D ⁻¹ b  (94),

where

D=Re(X)^(T) WRe(X)+Im(X)^(T) WIm(X)  (95), and

b=Re(X)^(T) WRe(y)+Im(X)^(T) WIm(y)  (96).

To find an expression for D in terms of the complex response vector Gand the natural frequency s=jω we first split X into its real andimaginary parts as illustrated in Equations (97) and (98), respectively,as follows:

$\begin{matrix}{{{{Re}(X)} = \begin{bmatrix}1 & {\omega_{k}{{Im}\left( G_{1} \right)}} & {- {{Re}\left( G_{1} \right)}} \\\vdots & \vdots & \vdots \\1 & {\omega_{k}{{Im}\left( G_{k} \right)}} & {- {{Re}\left( G_{k} \right)}}\end{bmatrix}},{and}} & (97) \\{{{Im}(X)} = {\begin{bmatrix}0 & {{- \omega_{k}}{{Re}\left( G_{1} \right)}} & {- {{Im}\left( G_{1} \right)}} \\\vdots & \vdots & \vdots \\0 & {{- \omega_{k}}{{Re}\left( G_{k} \right)}} & {- {{Im}\left( G_{k} \right)}}\end{bmatrix}.}} & (98)\end{matrix}$

The real and imaginary portions of the expression for D above thenbecome Equations (99) and (100), respectively:

                                          (99)${{{Re}(X)}^{T}W\; {{Re}(X)}} = {\quad{\begin{bmatrix}{\sum\limits_{i = 1}^{k}w_{i}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} \\{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}^{2}\omega_{i}^{2}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}}} \\{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}^{2}}}\end{bmatrix},\mspace{731mu} {{(100){{Im}(X)}^{T}W\; {{Im}(X)}} = {\begin{bmatrix}0 & 0 & 0 \\0 & {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}^{2}\omega_{i}^{2}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}} \\0 & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}^{2}}}\end{bmatrix}.}}}}$

Combining these terms gives the final expression for the D matrix. Thismatrix will contain only real values, as shown in Equation (101) asfollows:

                                          (101) $D = {\begin{bmatrix}{\sum\limits_{i = 1}^{k}w_{i}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} \\{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {\sum\limits_{i = 1}^{k}{{w_{i}\begin{pmatrix}{{{Re}\left( G_{i} \right)^{2}} +} \\{{Im}\left( G_{i} \right)^{2}}\end{pmatrix}}\omega_{i}^{2}}} & 0 \\{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} & 0 & {\sum\limits_{i = 1}^{k}{w_{i}\begin{pmatrix}{{{Re}\left( G_{i} \right)^{2}} +} \\{{Im}\left( G_{i} \right)^{2}}\end{pmatrix}}}\end{bmatrix}.}$

The same approach can be taken to find an expression for the b vector interms of G and ω. The real and imaginary parts of y are illustrated inEquation 102-103.

$\begin{matrix}{{{{Re}(y)} = \begin{bmatrix}{{- {{Re}\left( G_{1} \right)}}\omega_{1}^{2}} \\\vdots \\{{- {{Re}\left( G_{k} \right)}}\omega_{k}^{2}}\end{bmatrix}},{and}} & (102) \\{{{Im}(y)} = {\begin{bmatrix}{{- {{Im}\left( G_{1} \right)}}\omega_{1}^{2}} \\\vdots \\{{- {{Im}\left( G_{k} \right)}}\omega_{k}^{2}}\end{bmatrix}.}} & (103)\end{matrix}$

Combining these two gives the expression for the b vector illustrated inEquation 104 as follows:

$\begin{matrix}{b = {{{{{Re}(X)}^{T}W\; {{Re}(y)}} + {{{Im}(X)}^{T}W\; {{Im}(y)}}} = {\begin{bmatrix}{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}\omega_{i}^{2}}}} \\0 \\{\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}\omega_{i}^{2}}}\end{bmatrix}.}}} & (104)\end{matrix}$

The next step is to invert the D matrix. The matrix is symmetric andpositive-definite so the number of computations needed to find theinverse will be reduced from the general 3×3 case. The generalexpression for a matrix inverse is shown in Equation (105) as:

$\begin{matrix}{D^{- 1} = {\frac{1}{\det (D)}{{{adj}(D)}.}}} & (105)\end{matrix}$

If D is expressed as in Equation (106):

$\begin{matrix}{{D = \begin{bmatrix}d_{11} & d_{12} & d_{13} \\d_{12} & d_{22} & 0 \\d_{13} & 0 & d_{33}\end{bmatrix}},} & (106)\end{matrix}$

then the adjugate matrix can be written as in Equation (107) as follows:

$\begin{matrix}{{{adj}(D)} = {\quad{\begin{bmatrix}{\begin{matrix}d_{22} & 0 \\0 & d_{33}\end{matrix}} & {- {\begin{matrix}d_{12} & 0 \\d_{13} & d_{33}\end{matrix}}} & {\begin{matrix}d_{12} & d_{22} \\d_{13} & 0\end{matrix}} \\{- {\begin{matrix}d_{12} & d_{13} \\0 & d_{33}\end{matrix}}} & {\begin{matrix}d_{11} & d_{13} \\d_{13} & d_{33}\end{matrix}} & {- {\begin{matrix}d_{11} & d_{12} \\d_{13} & 0\end{matrix}}} \\{\begin{matrix}d_{12} & d_{13} \\d_{22} & 0\end{matrix}} & {- {\begin{matrix}d_{11} & d_{13} \\d_{12} & 0\end{matrix}}} & {\begin{matrix}d_{11} & d_{12} \\d_{12} & d_{22}\end{matrix}}\end{bmatrix} = {\begin{bmatrix}a_{11} & a_{12} & a_{13} \\a_{12} & a_{22} & a_{23} \\a_{13} & a_{32} & a_{33}\end{bmatrix}.}}}} & (107)\end{matrix}$

Due to symmetry, only the upper diagonal matrix needs to be calculated.The Determinant can then be computed in terms of the adjugate matrixvalues, taking advantage of the zero elements in the original array asillustrated in Equation (108) as follows:

det(D)=a ₁₂ d ₁₂ +a ₂₂ d ₂₂  (108).

Finally, the inverse of D can be written in the form shown in Equation(109):

$\begin{matrix}{D^{- 1} = {\frac{1}{\det (D)}{{{adj}(D)}.}}} & (109)\end{matrix}$

In some embodiments, we may solve the value in Equation (110):

$\begin{matrix}{{c = {{D^{- 1}b} = {\frac{1}{\det (D)}{{adj}(D)}b}}};} & (110)\end{matrix}$

So that Equation (111) is used:

$\begin{matrix}{{c = {{{\frac{1}{\det (D)}\begin{bmatrix}a_{11} & a_{12} & a_{13} \\a_{12} & a_{22} & a_{23} \\a_{13} & a_{32} & a_{33}\end{bmatrix}}\begin{bmatrix}b_{1} \\0 \\b_{3}\end{bmatrix}} = {\frac{1}{\det (D)}\begin{bmatrix}{{a_{11}b_{1}} + {a_{13}b_{3}}} \\{{a_{12}b_{1}} + {a_{23}b_{3}}} \\{{a_{13}b_{1}} + {a_{33}b_{3}}}\end{bmatrix}}}},} & (111)\end{matrix}$

To get a quantitative assessment of how well the data fits the model,the original expression for the error as shown in Equation (112) isutilized:

e ^(T) We=Re(y−Xc)^(T) WRe(y−Xc)+Im(y−Xc)^(T) WIm(y−Xc)  (112).

This can be expressed in terms of the D matrix and the b and c vectorsillustrated in Equation (113):

e ^(T) We=h−2c ^(T) b+c ^(T) Dc  (113),

where:

$\begin{matrix}{{h = {{{{Re}\left( y^{T} \right)}W\; {{Re}(y)}} + {{{Im}\left( y^{T} \right)}W\mspace{11mu} {{Im}(y)}}}},{and}} & (114) \\{h = {\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}{\omega_{i}^{4}.}}}} & (115)\end{matrix}$

In some embodiments, to compare the errors from different sine sweeps,the fit error is normalized by the square of the weighted by matrix asfollows in Equation (116), where h is a scalar:

e ^(T) Weh ⁻¹=(h−2c ^(T) b+c ^(T) Dc)h ⁻¹  (116).

Volume Estimation Using Swept Sine-Estimating Volume

The model fit may be used such that the resonant frequency of the portmay be extracted from the sine sweep data. The delivered volume may berelated to this value. The ideal relationship between the two can beexpressed by the relation illustrated in Equation (117):

$\begin{matrix}{\omega_{n}^{2} = {\frac{a^{2}A}{L}{\frac{1}{V_{2}}.}}} & (117)\end{matrix}$

The speed of sound will vary with the temperature, so it is useful tosplit out the temperature effects as shown in Equation (118):

$\begin{matrix}{\omega_{n}^{2} = {\frac{\gamma \; {RA}}{L}{\frac{T}{V_{2}}.}}} & (118)\end{matrix}$

The volume can then be expressed as a function of the measured resonantfrequency and the temperature, illustrated in Equation (119) as follows:

$\begin{matrix}{V_{2} = {C{\frac{T}{\omega_{n}^{2}}.}}} & (119)\end{matrix}$

Where C is the calibration constant illustrated in Equation (120) asfollows:

$\begin{matrix}{C = {\frac{\gamma \; {RA}}{L}.}} & (120)\end{matrix}$

Volume Estimation Using Swept Sine-Volume Estimation Integrity Checks

In some embodiments, a second set of integrity check can be performedout of the output of the mode fit and volume estimation routines (thefirst set of checks is done at the FFT level). Checks may be done eitherthrough redundancy or through range checking for several values, suchas: (1) model fit error, (2) estimated damping ratio, (3) estimatedtransfer function gain, (4) estimated natural frequency, (5) estimatedvariable volume, and (6) AVS sensor temperature.

In addition, portions of the AVS calculations may be done redundantly onthe a processor disclosed herein using an independent temperature sensorand an independent copy of the calibration parameters to guard againstRAM failures, in some specific embodiments.

Volume Estimation Using Swept Sine-Disposable Detection

The presence of the disposable, e.g., cartridges or reservoirs that areattachable, may be detected using a magnetic switch and mechanicalinterlock, in some specific embodiments. However, a second detectionmethod may be used to 1) differentiate between the pump being attachedto a disposable and a charger, and 2) provide a backup to the primarydetection methods.

If the disposable is not present, the variable volume, V2, iseffectively very large. As a result, there will be a normal signal fromthe reference microphone, but there will be very little signal on thevariable microphones. If the mean amplitude of the reference microphoneduring a sine sweep is normal (this verifies that the speaker isworking) and the mean amplitude of the variable microphone is small, aflag is set in the a processor disclosed herein indicating that thedisposable is not present.

Implementation Details-Sizing V1 Relative to V2

Sizing V₁ may include trading off acoustic volume with the relativeposition of the poles and zeros in the transfer function. The transferfunction for both V₁ and V₂ are shown below relative to the volumedisplacement of the speaker as illustrated in Equations 121-124, asfollows:

$\begin{matrix}{{\frac{p_{2}}{v_{k}} = {{- \frac{\rho \; a^{2}}{V_{1}}}\frac{\omega_{n}^{2}}{s^{2} + {2\; \zeta \; \omega_{n}s} + {\alpha \; \omega_{n}^{2}}}}},{and}} & (121) \\{\frac{p_{1}}{v_{k}} = {{- \frac{\rho \; a^{2}}{V_{1}}}\frac{s^{2} + {2{\zeta\omega}_{n}s} + {\alpha \; \omega_{n}^{2}}}{s^{2} + {2\; \zeta \; \omega_{n}s} + \; \omega_{n}^{2}}}} & (122)\end{matrix}$

where

$\begin{matrix}{{\omega_{n}^{2} = {\frac{a^{2}A}{L}\frac{1}{V_{2}}}},{\zeta = {\frac{fA}{2L\; \omega_{n}}\mspace{14mu} {and}}}} & (123) \\{\alpha = {\left( {1 + \frac{\; V_{2}}{V_{1}}} \right).}} & (124)\end{matrix}$

As V₁ is increased the gain decreases and the speaker must be driven ata higher amplitude to get the same sound pressure level. However,increasing V₁ has the benefit of moving the complex zeros in the p₁transfer function toward the complex poles. In the limiting case whereV₁→∞ then α→1 and you have pole-zero cancellation and a flat response.Increasing V₁, therefore, has the reduces both the resonance and thenotch in the p₁ transfer function, and moves the p₂ poles toward ω_(a);the result is a lower sensitivity to measurement error when calculatingthe p₂/p₁ transfer function.

Implementation Details-Aliasing

Higher frequencies can alias down to the frequency of interest. Thealiased frequency can be expressed in Equation (125) as follows:

f=|f _(n) −nf _(s)|  (125).

Where f_(s) is the sampling frequency, f_(n) is the frequency of thenoise source, n is a positive integer, and f is the aliased frequency ofthe noise source.

The demodulation routine may filter out noise except at the specificfrequency of the demodulation. If the sample frequency is setdynamically to be a fixed multiple of the demodulation frequency, thenthe frequency of the noise that can alias down to the demodulationfrequency will be a fixed set of harmonics of that fundamentalfrequency.

For example, if the sampling frequency is 8 times the demodulationfrequency then the noise frequencies that can alias down to thatfrequency are

$\begin{matrix}{\frac{f_{n}}{f} = {\left\{ {\frac{1}{{n\; \beta} + 1},\frac{1}{{n\; \beta} - 1}} \right\} = \left\{ {\frac{1}{7},\frac{1}{9},\frac{1}{15},\frac{1}{17},\frac{1}{23},\frac{1}{25},\ldots} \right\}}} & (126)\end{matrix}$

where

$\begin{matrix}{\beta = {\frac{f_{s}}{f} = 8.}} & (127)\end{matrix}$

For β=16 we would have the series

$\begin{matrix}{\frac{f_{n}}{f} = {\left\{ {\frac{1}{15},\frac{1}{17},\frac{1}{31},\frac{1}{33},\ldots}\; \right\}.}} & (127)\end{matrix}$

Sources of Avs Measurement Error-Avs Chamber Movement

In some embodiments, one of the assumptions of the AVS measurement isthat the total AVS volume (V₂ plus the volume taken up the by the othercomponents) is constant. However, if the AVS housing flexes the totalvolume of the AVS chamber may change slightly and affect thedifferential volume measurement. In some embodiments, to keep thecontribution of the volume error is kept to be less than 1.0% of thefluid delivery.

Sources of Avs Measurement Error-External Noise

In some embodiments, external noise sources may be filtered out.

Sources of Avs Measurement Error-Mechanical Shock

Mechanical shock to the pump housing during an AVS measurement willaffect the microphone measurements and may result in an error in thefrequency response data. This error, however, is detectable using theout-of-band variance check in the demodulation routine by the aprocessor disclosed herein. If such an error is detected, the data pointcan be repeated (e.g., another sample is taken) resulting in little orno effect on the resulting AVS measurement.

Sources of Avs Measurement Error-Air in the AVS Chamber

A mechanism for an air bubble to affect the AVS measurement is through asecondary resonance. This secondary resonance will make the system4^(th) order and, depending on the frequency and magnitude of thesecondary resonance, can cause some error if the estimation is using a2^(nd) order model.

Sources of Avs Measurement Error-Electrical Component Failure

In general, failure an electrical component will result in no signal orin increased harmonic distortion. In either case the fault would bedetected by AVS integrity checks and the measurement invalidated.

The one exception that has been identified is a failure of theoscillator used to control the DAC and ADC. If this oscillator were todrift out of tolerance it would introduce a measurement error that wouldnot be detected by the low-level integrity check (it would be detectedin an extreme case by the volume integrity checks described above). Toguard against these failures, in some embodiments, the oscillator ischecked against an independent clock whenever an AVS measurement isinitiated.

L-Shaped Cam Follower Peristaltic Pump

FIGS. 255-302 show another embodiment of a peristaltic pump 2990.

FIG. 255 illustrates a peristaltic pump 2990 comprising a pumpingmechanism 3000, display 2994, buttons 2996, chassis 2992, and clamp2998. The chassis 2992 includes an extension 2992A above the pumpingmechanism 3000 that deflects liquid away from the inside of themechanism.

FIGS. 256A-B illustrate a peristaltic pumping mechanism 3000 havingL-shaped cam followers 3090, 3101, 3110 (see FIG. 274) in an explodedview. A housing, composed optionally of two halves, 3005, 3010 providesa mounting for a cam shaft 3080, a main PCB 3002, a cam-follower shaft3120, a gear head assembly 3070, and hinge points 3010A to mount a door3020. The two halves 3005, 3010 may be an upper half 3010 and a lowerhalf 3005. The sensor housing 3015 may mount to the housing halves 3005,3010 and provide an attachment point to a sensor mount 3060 and arotation sensor board 3130 (FIG. 257). An air-in-line detector 3066 (seeFIG. 257) and a pressure sensor 3068 (FIG. 257) may be attached to thesensor mount 3060.

FIG. 257 illustrates the pumping mechanism 3000 having L-shaped camfollowers 3090, 3101, 3110 (see FIG. 274) with the door assembly 3021fully open and the infusion line 3210 and slide occluder 3200 mounted inthe door 3020. The door assembly 3021 is mounted to the housing halves3010, 3005 via two hinges 3010A and a hinge pin 3012 (FIG. 258). In theopen position, the door assembly 3021 may provide convenient receivingelements, which may serve to locate an infusion line 3210 on the doorassembly 3021. The receiving elements may locate the infusion line 3210so that it properly interfaces or lines up with the sensors and activeelements of the peristaltic pump 2990. The sensors may, for example,include a pressure sensor 3068 (FIG. 257) and/or an air-in-line sensor3066 (FIG. 257). The active elements may include, for example, theplunger 3091, inlet valve 3101 and outlet valve 3111 (FIG. 260). Thereceiving elements in the door 3020 may include one or more of thefollowing: grooves in the door 3020K (see FIG. 259), clips 3062A (FIG.257), clip inserts 3024 (FIG. 257), platen 3022 (FIG. 257, 259). Theclips 3062A (FIG. 257) and 3024 (FIG. 257) may be fabricated out of anysuitable, non-deformable, non or minimally compliant material. The clips3062A are preferably molded from plastic such as nylon, but many othermaterials including ABS plastic, aluminum, steel or ceramics may beused.

The door assembly 3021 (FIG. 257) may include a receiving element forthe slide occluder 3200. The slide occluder 3200 receiving elements inthe door assembly 3021 may hold the slide occluder 3200 in position sothat the slide occluder 3200 enters a receiving opening in the pump body3001 (FIG. 265). Some of the slide occluder 3200 receiving elements mayinclude features that prevent the infusion set from being loadedincorrectly. In one embodiment, door split carriage 3040 includes a slotto receive the slide occluder 3200 and hold it perpendicular to theinfusion line 3210 as the door assembly 3021 is closed against the pumpbody 3001. The slide occlude 3200 may include tabs 3040C (FIG. 259) thatallow the slide occluder 3200 to only be inserted such that cutouts3200A (FIG. 261) line up with tabs 3040C (FIG. 261). In anotherembodiment, the door 3020 may include tabs 3020F (FIG. 262, 263) thatallow the slide occluder 3200 to only be inserted such that cutouts3200A (FIG. 261) line up with tabs 3020F (FIG. 262). The door 3020 (FIG.257) may include tabs 3020D (FIG. 259) that prevent the slide occluder3200 (FIG. 257) from being inserted with the tab 3200B (FIG. 261) towardthe door assembly 3021 (FIG. 257). The tabs 3020F located on the door3020 and/or on the door-split-carriage 3040 (FIG. 257) may allow theslide occluder 3200 to be inserted in only one orientation and therebyforce the correct orientation between the infusion set and the pumpingmechanism 3000. The platen 3022 (FIG. 257) receives the infusion line3210 and provides a general “U” shape to constrain the infusion line3210 as a plunger 3091 deforms the infusion line 3210 during pumping.

FIG. 264 illustrates, in an exploded view, the door assembly 3021including the lever 3025 and the split carriage 3041 of the peristalticpumping mechanism 3000 (FIG. 257) having L-shaped cam followers 3090,3101, 3110 (see FIG. 274). Infusion line 3210 receiving elements 3062,3022 (FIG. 260) 3024 (FIG. 257) may be mounted respectively in recesses3020A, 3020B, 3020E of the door 3020. The door assembly 3021 may includea door split carriage 3040 that is connected to the lever 3025 via link3035. The door assembly 3021 may also include a flat spring 3032 that isa sheet of resilient material such as spring-steel. The flat spring 3032may be pressed against the door 3020 by the latch pin 3034 as the lever3025 grips the body pins 3011 (FIG. 297) on the pump body 3001 and drawsthe latch pin 3034 toward the pump body 3001. The latch pin 3034 movesalong slot 3020C in the door 3020 as the latch hooks 3025C engage thebody pins 3011.

FIG. 265 illustrates the peristaltic pump 2990 (FIG. 255) havingL-shaped cam followers 3090, 3101, 3110 (see FIG. 274) with the doorassembly 3021 open and the lever 3025 retracted. The main PCB 3002,which includes the control processors and some sensors is shown attachedto the top of the upper housing 3010. A motor 3072 and gear head 3070are shown in position at one end of the upper housing 3010. The rotationsensor assembly 3130 may be mounted on the lower housing half 3005. Thepump body 3001 may comprise housing halves 3005, 3010, the rotating, andreciprocating mechanisms inside the housing halves 3005, 3010, the motor3072 and gearbox 3070, the sensors and the structure in which the abovemount.

FIG. 260 illustrates the peristaltic pump 2990 (FIG. 255) havingL-shaped cam followers 3090, 3101, 3110 (see FIG. 274) with the door3020 open and the upper housing 3010 and other elements removed toreveal the cam-shaft 3080, the plunger 3091 and valves 3101, 3111. Themotor 3072 drives the cam shaft 3080 through the gearbox 3070. The motor3072 may have a drive shaft whose the speed and/or position can becontrolled. In one embodiment the motor 3072 is a brushless DCservo-motor 3072 controlled by a motor controller 3430 (see FIG. 325B)that may be mounted on the main PCB 3002. In alternative embodiments,the motor 3072 may be a stepper motor 3072, a DC brushed motor 3072 oran AC motor 3072 with the appropriate controller.

The motor 3072 may be fixedly coupled to the gearbox 3070 allowing themotor/gearbox unit to be attached as a unit to the cam shaft 3080 andupper housing 3010. The gear reduction of the gearbox 3070 increases thetorque, while increasing the number of motor 3072 rotations per rotationof the cam shaft 3080 (FIG. 260). In one embodiment, the gearbox 3070has a reduction ratio of 19:1. The gear reduction allows reasonableresolution on the cam shaft 3080 (FIG. 260) position with a relativelyfew number of hall sensors in the motor 3072. In one embodiment, threehall sensors and eight windings produce twenty-four crossings perrevolution. The twenty-four crossings combined with a 19:1 gear ratioprovides better than 0.8° angular resolution on the cam shaft 3080 (FIG.260) rotation.

The rotation of the cam shaft 3080 (FIG. 260) may be directly measuredwith a rotation sensor 3130 (FIG. 257) that detects the position of themagnet 3125 on the end of the cam shaft 3080 (FIG. 260). In oneembodiment, the sensor is a single-chip magnetic rotary encoder IC thatemploys 4 integrated Hall elements that detect the position of themagnet 3125 (FIG. 260), a high resolution analog to digital converterand a smart power management controller. The angle position, alarm bitsand magnetic field information may be transmitted over a standard 3-wireor 4-wire SPI interface to a host controller. One example of a rotaryencoder is model AS5055 manufactured by Austriamicrosystems of Austriathat provides 4096 increments per rotation.

The movements of the valve 3101, 3110, and the plunger 3090 arecontrolled by the rotation of the cam shaft 3080 that turns individualcams 3083, 3084, 3082 (FIG. 266), which in turn deflects a roller end3092, 3102, 3112 (FIG. 274) of the L-shaped followers 3090, 3100, 3110(FIG. 274) downward. The L-shaped cam followers 3090, 3100, 3110 (FIG.274) rotate about the cam-follower shaft 3120, so downward movement ofthe roller end 3092, 3102, 3112 causes the active end to pull away fromthe infusion line 3210 (FIG. 276). Torsional springs 3094, 3104, 3114(FIG. 274) on each of the L-shaped cam followers 3090, 3100, 3110 (FIG.274) urge the rollers 3092, 3102, 3112 upward against the cams 3082,3083, 3084 (FIG. 276) and urge the active ends 3091. 3101, 3111 towardthe infusion line 3210.

The profiles of the outlet valve cam 3084, plunger cam 3083, and inletvalve cam 3082 are pictured in FIGS. 271-273. These profiles produce avalve sequence similar to that plotted in FIG. 197. The cams 3084, 3083,3082 may be connected to the cam shaft 3080 in any of the standardmethods including adhesive, press fit, keyed shaft. In some embodiments,the cams 3084, 3083, 3082 may be physically integrated into the camshaft 3080 as a single piece. In one embodiment, the cams 3084, 3083,3082 have a key slot 3082A, 3083A, 3084A and are pressed onto the camshaft 3080 against a shoulder (not shown) with a key (not shown) torotationally locate the cams 3084, 3083, 3082 on the cam shaft 3080 anda circle clip 3085 to hold the cams 3084, 3083, 3082 in position alongthe axis of the cam shaft 3080. The cam shaft 3080 is mounted in theupper and lower housings 3005, 3010 by bearings 3086. In one embodiment,the bearings 3086 are sealed roller bearings.

FIG. 274 illustrates the plunger L-shaped follower 3090, valve L-shapedcam followers 3101, 3110 and cam-follower shaft 3120 in an explodedview. The L-shaped cam followers 3090, 3100, 3110 mount on thecam-follower shaft 3120 and rotate freely on the cam-follower shaft3120. The rotation of the L-shaped cam followers 3090, 3100, 3110 on thecam-follower shaft 3120 may be facilitated by bearings. In oneembodiment, the bearings are solid flanged bushings 3095, 3105, 3115pressed into the bodies 3093, 3103, 3113 of the L-shaped cam followers3090, 3100, 3110. The bearings may be any low friction bushing includingbronze, brass, plastic, nylon, polyacetal, polytetrafluoroethylene(PTFE), ultra-high-molecular-weight polyethylene (UHMWPE), rulon, PEEK,urethane, and vespel. The flanges on the bushings 3095, 3105, 3115 mayserve as axial bearing surfaces between adjacent L-shaped cam followers3090, 3100, 3110 and between the valve L-shaped cam followers 3101, 3110and the housing halves 3005, 3010 (FIG. 265). The flanges on thebushings 3095, 3105, 3115 (FIG. 274) may also serve to properly spacethe active ends 3091, 3101, 3111 (FIG. 274) of the L-shaped camfollowers 3090, 3100, 3110 (FIG. 274) relative to platen 3022 (FIG. 257)on the door assembly 3021 (FIG. 257).

The cam-follower shaft 3120 (FIG. 274) may include end sections 3120A(FIG. 274) that are eccentric relative to the center section 3120B (FIG.274) of the cam-follower shaft 3120 (FIG. 274). The position of thecam-follower shaft 3120 (FIG. 274) relative to the cam-shaft 3080 (FIG.260) and/or platen 3022 (FIG. 260) may be finely adjusted by turning theeccentric end 3120A. Turning the eccentric end 3120A allows adjustmentof the lash between rollers 3092, 3102, 3112 and the cams 3084, 3083,3082 (FIGS. 271-273) on the cam shaft 3080 (FIG. 260).

The end section 3120A of the cam-follower shaft 3120 (FIG. 274) mayinclude a feature 3120C to receive a tool such as a screw driver, hexkey or other tool capable of applying a torque to the cam-follower shaft3120 (FIG. 274). In one embodiment, the feature is a slot sized toaccept a slot-headed screw driver. The eccentric ends 3120A fit in holesformed by cut-outs 3005D, 3010D (see FIG. 278) in the housing halves3005, 3010 respectively. In one embodiment, the holes formed by cutouts3005D, 3010D (FIG. 278) do not bind the cam-follower shaft 3120 (FIG.274) in order to allow adjustment. A clamping element may be added tosecure the rotary position of the cam-follower shaft 3120 (FIG. 274). Inone embodiment, the clamping element is a set screw in threaded hole3120A.

The L-shaped cam followers 3090, 3100, 3110 (FIG. 274) or actuatorscomprise rollers 3092, 3102, 3112 that touch the cams 3084, 3083, 3082(FIGS. 271-273), an elastic element 3094, 3104, 3114 that urges thecontacting element toward the cam surface, and an L-shaped structure3093, 3103, 3113 that includes a bore, which mounts on the cam-followershaft 3120 and connects the rollers 3092, 3102, 3112 to the activeelement 3091, 3101, 3111 that in turn touches the infusion line 3210.The L-shaped cam followers 3090, 3100, 3110 (FIG. 274) additionallyinclude flanged bearings 3095, 3105, 3115 mounted in the bore of thestructure 3093, 3103, 3113 (FIG. 274).

In one embodiment, the rollers 3092, 3102, 3112 rotate about a shaft3096, 3106, 3116 that is mounted in the structures 3093, 3103, 3113(FIG. 274). Rollers are preferred as the contacting element in order toreduce the load on the motor 3072 and improve peristaltic pump 2990repeatability. In other embodiments a different type of contactingelement may be used.

In one embodiment, the active elements, or inlet valve 3101, plunger3091, an outlet valve 3111, are formed as part of the L-shaped camfollowers 3090, 3100, 3110 (FIG. 274). In one embodiment, the activeelements, 3091, 3101, 3111 are removably attached to the structure ofeach L-shaped cam follower 3090, 3100, 3110 (FIG. 274). In oneembodiment, the active elements 3091, 3101, 3111 (FIG. 274) may bemechanically attached with screws. In other embodiments, the activeelements 3091, 3101, 3111 (FIG. 274) may include studs that pass throughholes in the structures 3093, 3103, 3113 (FIG. 274) and are held inplace with nuts, or the active elements 3091, 3101, 3111 (FIG. 274) mayinclude plastic studs that snap into receiving elements in thestructures 3093, 3103, 3113 (FIG. 274).

The elastic elements 3094, 3104, 3114 urge the L-shaped cam followers3090, 3100, 3110 (FIG. 274) against the cam surfaces of the cams 3084,3083, 3082 (FIGS. 271-273) and toward the platen 3022 (FIG. 260) andinfusion line 3210. In one embodiment, the elastic elements 3094, 3104,3114 (FIG. 274) are coiled torsion springs that wrap around the sectionof the structures 3093, 3103, 3113 (FIG. 274) that includes the bore.One end of the torsion springs press against the L-shaped cam followerstructures 3090, 3100, 3110 (FIG. 274) between the bore and the rollers3092, 3102 and 3112. The other end of the spring contacts the fixedstructure of the peristaltic pump 2990. In one embodiment the other endof each spring contacts a spring retainer 3140 (FIGS. 275, 276) that mayinclude a slot 3140A to capture the spring end. A retainer set screw3142 (FIG. 275) can be turned to move the spring retainer 3140 withinthe upper housing 3010 and apply a load against the elastic elements3094, 3104, 3114. At some cam 3084, 3083, 3082 (FIGS. 271-273) rotarypositions, the load applied to the spring will in turn be applied by theactive ends 3091, 3101, 3111 to the infusion line 3210. The compressiveload of each active ends 3091, 3101, 3111 (FIG. 274) on the infusionline 3210 may be adjusted by turning the corresponding retainer setscrew 3142.

In another embodiment, the elastic elements 3094, 3104, 3114 (FIG. 274)are helical springs that are located between the L-shaped cam followers3090, 3100, 3110 (FIG. 274) and the structure of the pump body 3001. Thehelical springs are located such that they urge the follower-end orroller-end of the L-shaped cam followers 3090, 3100, 3110 (FIG. 274)toward the cams 3082, 3083, 3084 (FIG. 271-273). The helical springs mayalso urge the active end of the L-shaped cam followers 3090, 3100, 3110(FIG. 274) toward the platen 3022 (FIG. 260). One arrangement of helicalsprings and L-shaped cam followers 3090, 3100, 3110 is shown in FIGS.205, 206, 219, 220.

FIG. 276 shows a cross-section of the pump mechanism 3000 includingsections of the plunger cam 3083, plunger 3091 and platen 3022. The camshaft 3080 turns the plunger cam 3083 which is keyed to the shaft at3084A. The cam 3083 displaces the cam contacting element or cam roller3092, which is part of the plunger 3091 L-shaped cam follower 3090. Theplunger 3091 L-shaped cam follower 3090 rotates about the cam-followershaft 3120. The plunger 3091 L-shaped cam follower 3090 is held againstthe plunger cam 3083 by the elastic element 3094. One end of the elasticelement 3094A contacts the structure 3093, while the free end of theelastic element 3094B contacts the spring retainer 3140. The plunger3091 compresses the infusion line 3210 against the platen 3022. Theplunger 3091 retracts from the platen 3022, when the plunger cam 3083depresses the cam-roller 3092.

FIG. 277 presents a cross-section of the plunger 3091, platen 3022 andinfusion line 3210 at the bottom of the plunger 3091 stroke. At the topof the plunger 3091 stroke, the non compressed infusion line 3210 has anominally round cross section that contains a maximum volume. Thepumping mechanism 3000 maximizes pumping per stroke by allowing theinfusion line 3210 to completely fill at the top of the stroke andminimize the volume inside the infusion line 3210 at the bottom of theplunger 3091 stroke. The amount of volume pumped may be impacted by theshape of the plunger 3091, the length of the plunger 3091 stroke and theshape of the platen 3022. However, if the infusion line 3210 iscompletely crushed, the forces on the plunger 3091 may be higher thanneeded, which may necessitate larger elastic elements 3090, 3100, 3110(FIG. 274) and or a larger motor 3072 or higher power draw. The higherpower draw may shorten the time the peristaltic pump 2990 can run on abattery 3420 or may create a heavier peristaltic pump 2990 due to alarge battery 3420. The design of the plunger 3091 and platen 3022 maybe selected to balance increased volume against higher loads on theplunger 3091. In one embodiment, the plunger 3091 and platen 3022 aredesigned to avoid compressing infusion line 3210 walls by providing agap between the plunger 3091 and the platen 3022 that is slightly largerthan two times the infusion line 3210 wall thickness.

In one embodiment, the plunger cam 3083 and plunger L-shaped camfollower 3090 are designed provide a minimum clearance 3022G between thetip of the plunger 3091B and the bottom of the platen 3022D. In oneexample, the clearance 3022G is 2 to 3 times the infusion line 3210 wallthickness and sufficient such that the infusion line 3210 walls do nottouch between the plunger tip 3091B and platen bottom 3022D. In oneexample, the clearance 3022G between the plunger tip 3091B and thebottom of the platen 3022D is approximately 0.048″, which is 9% largerthan twice the wall thickness of an example infusion line 3210. Inanother example, the clearance 3022G may be as small as 2% larger thantwice the wall thickness of an example infusion line 3210. In anotherexample the clearance 3022G may be as large as 50% larger than twice thewall thickness of an infusion line 3210.

In one embodiment, the dimensions of the platen 3022 and plunger tip3091B are selected to provide a clearance 3022G that is 2 to 3 times thewall thickness of a single wall of the infusion line 3210. In oneexample, the clearance 3022G between the plunger tip 3091B and theplaten 3022 is 8% to 35% larger than twice the wall thickness of anexample infusion line 3210. The clearance 3022G will allow the sides ofthe infusion line 3210 to fold without pinching the fold shut. In oneembodiment, the plunger tip 3091B has a radius of 0.05″ and sides 3091Cthat have an angle between them of 35°. The sides 3091C may meet theplunger tip 3091B radius at a tangent angle. The length of the plungertip 3091D may be 0.116″. The platen bottom 3022D may be flat and have aradius 3022C on each side. The length of the platen bottom 3022D andradii 3022C are selected to maintain a clearance 3022G between theplunger tip 3091B and the platen 3022 that is more than twice theinfusion line 3210 wall thickness. In one example, the platen bottom3022D is 0.05 long and each radius 3022C is 0.06″. Side 3022B is angledaway from the plunger 3091. The shorter side 3022E is nearly vertical.Side 3022F is at a less vertical angle than the plunger walls 3091C toallow the plunger tip 3091B to enter the platen 3022 as the doorassembly 3021 is closed.

The plunger 3091 and platen 3022 may include two flat sections 3091A and3022A which provide a mechanical stop. The flat sections 3091A and 3022Amay also be referred to herein as stops 3091A and 3022A. The mechanicalstops 3091A, 3022A may improve the reliability and reduce theuncertainty of the volume measurement. As described elsewhere, thevolume is determined from the change in plunger 3091 position from thebeginning of the displacement stroke to the end of stroke. The stops3091A and 3022A may remove the uncertainty or tolerance in the bottom ofstroke measurement. The profile on the plunger cam 3083 may be designedto lift off the roller 3092, when the flat section 3091A contacts theplaten 3022 at 3022A.

The plunger 3091 and platen 3022 may be formed of with a surface thateasily slides on an infusion line 3210 material of PVC or Non-DEHP. Inone embodiment, the plunger 3091 and platen 3022 may be formed of nylon.In another embodiment, the plunger 3091 and platen 3022 may be metal(e.g. aluminum) that is coated with PTFE. In other embodiments, otherplastic may be used or other coatings applied to a metal plunger 3091and/or platen 3022 that provide a low friction coefficient with a PVC orNon-DEHP infusion line 3210.

The cam shaft 3080 and the cam-follower shaft 3120 are mounted incut-outs 3005C, 3005D, 3010C, 3010A in the lower and upper housing 3005,3010 as shown in FIGS. 260, 278. The accuracy of the movements of thevalves 3101, 3111 and the plunger 3091 as well as the usage life of theroller elements 3092, 3102, 3112 and cams 3082-3084 are improved bybetter parallel alignment and correct spacing of the two shafts 3080,3120. The parallel alignment and spacing of the two shafts 3080, 3120are controlled in part by the parallel alignment and spacing of thecutouts 3005C, 3005D, 3010C, 3010A. In one embodiment, the two parts ofthe housing 3005, 3010 are formed without the cutouts (FIGS. 278, 279).The two parts are then mechanically joined and the holes 3006, 3007 aredrilled or bored by the same machine in the same setup (FIG. 280) at thesame time. In some embodiments, the two housing parts 3005, 3010 includefeatures to hold them in a fixed alignment with one another whenassembled. In one example, the housing 3005, 3010 alignment features arepins pressed in one part and matching holes in the other. In anotherexample, features on one part extend across the split line 3008 toengage features on the other part. The operation of accurately boringholes is sometimes referred to as line boring. Line boring may improvethe parallel alignment of the cutouts 3005C, 3005D, 3010C, 3010A. Theline boring of the cutouts 3005C, 3005D, 3010C, 3010A in the joinedhousing 3005, 3010 inexpensively creates cutouts 3005C, 3005D, 3010C,3010A that combine to form more accurately circular holes 3006, 3007 andholes 3006, 3007 that are more parallel one to another.

The measurement of pumped volume is based on the measured position ofthe plunger 3091. In one embodiment as shown in FIGS. 281, 275, theplunger 3091 position is measured remotely without contacting theplunger 3091 L-shaped cam follower 3090. In one embodiment, the plunger3091 position is measured with a linear hall effect encoder IC 3002A anda simple two-pole magnet 3096A (FIG. 282). The linear encoder 3002A(FIG. 282) is located on the main PCB 3002 and reports the position ofthe magnet 3096A located on the plunger 3091 L-shaped cam follower 3090to the controller. The linear encoder IC 3002A is advantageouslymechanically disconnected from the moving components, so the sensor willnot wear, degrade or break with use. In one embodiment, the linearencoder IC 3002A is part AS5410 manufactured by Austriamicrosystems ofAustria. The AS5410 allows the conversion of a wide range of geometriesincluding curved movements, non-linear scales, and tilted chip/magnetgeometries into a linear output signal. The flexibility of the linearencoder IC 3002A allows larger tolerances in the placement of the mainPCB 3002 relative to the plunger magnet 3096A. Alternatively, theposition of the plunger 3091 may be measured with a vision system thatuses edges or datums located on the plunger 3091 L-shaped cam follower3090. Alternatively, the plunger 3091 position may be measured with anyof several sensors well known in the art including a linearpotentiometer, a rotary potentiometer, rotary encoder, linear encoder,or LVDT. Methods to mechanically connect one of these sensors to theplunger L-shaped cam follower 3090 may be those apparent to one skilledin the art.

The slide occluder 3200 can be seen in FIG. 261. The slide occluder 3200serves to pinch the infusion line 3210 closed, blocking flow, when theinfusion line 3210 is in the narrow part of the opening 3200D (FIG.261). Flow is allowed through the infusion line 3210 when it is locatedin the wide end of the opening 3200C at the front of the slide occluder3200. The open position on the slide occluder 3200 refers to theinfusion line 3210 being located in the wide end of the opening 3200C.The closed position of the slide occluder 3200 refers to the infusionline 3210 being located in the narrow part of the opening 3200D. Theslide occluder 3200 includes at least one opening 3200A on the front endof the slide occluder 3200. A tab 3200B is located at the back end ofthe slide occluder 3200.

The process of closing the door and inserting the slide carriage 3041 torelease the slide occluder 3200 is described with reference to FIGS. 283to 293. FIG. 283 illustrates the slide occluder 3200 fully inserted intothe door split carriage 3040 and the infusion line 3210 clipped into theclips 3062A, 3024. The door assembly 3021 will close by rotating aboutthe hinges 3010A. The initial position of the body split carriage 3045in the pump body 3001 can be seen in FIG. 284. The slot 3045E in thebody split carriage 3045 receives the slide occluder 3200 when the doorassembly 3021 is closed against the pump body 3001. The opening 3045B inthe body split carriage 3045 accommodates the tab 3200B of the slideoccluder 3200 allowing the back end of the slide occluder 3200 to enterthe body split carriage 3045 and allowing the door assembly 3021 toclose. The body split carriage 3045 and/or upper housing 3010 preventthe door assembly 3021 from closing when the slide occluder 3200 hasbeen incorrectly oriented. The side of the body split carriage 3045opposite the opening 3045B does not provide an opening or slot thatcould accommodate the tab 3200B on the slide occluder 3200. In oneembodiment, the upper housing 3010 includes a rail 3010E that blocks thetab 3200B.

FIG. 285 illustrates the two part split-carriage assembly 3041 in theopen position. Such a position may be reached when the door assembly3021 is open. FIG. 286 illustrates the two part split-carriage assembly3041 in the closed position. Such a position may be reached when thedoor assembly 3021 is closed against the pump body 3001. The axis of thehinge 3040B is approximately in line with the axis of the upper housing3010 hinge 3010A when the door assembly 3021 is open. The door splitcarriage 3040 includes at least one slot 3040D that allows it toaccommodate at least one tab 3020D on the door 3020 and rail 3010E inthe upper housing 3010. In an alternative embodiment shown in FIGS.262-263, the slot 3040D may accommodate or be guided on tabs 3020D,3020F. The body split carriage 3045 includes at least one slot 3045D toaccommodate rail 3010A on the upper housing 3010 and/or rail 3015E onthe sensor housing 3015. The slots 3040D and 3045D allow the splitcarriage 3041 to slide within the pump body 3001 and door 3020 when thedoor 3020 is closed against the body 3001.

FIG. 287 illustrates the peristaltic pump 2990 having L-shaped camfollowers 3090, 3100, 3110 with the door 3020 partially closed and someelements removed to reveal the slide occluder 3200 in the closedsplit-carriage 3041. The door assembly 3021 is closed and the lever 3025has not begun to engage the body pins 3011. The position of the splitcarriage 3041 comprising parts 3045 and 3040 is controlled by theposition of the lever 3025. The split carriage 3041 is pushed into thepump body 3001 by a rib 3025F as the lever 3025 is closed or rotatedtoward the pump body 3001. The split carriage 3041 is pulled partiallyout of the pump body 3001 by the lever link 3035 as the lever 3025 isopened or rotated away from the pump body 3001. The door split carriage3040 is connected to the lever 3025 via the closed end of the lever link3035C that fits over the carriage pin 3040A and the open end 3035B holdsa pin 3026 that slides in a slotted rib 3025A on the lever 3025. Thesplit carriage's 3041 travel is limited by the length of the slideoccluder 3200. The slide occluder 3200 which may not provide sufficientrotation of the lever 3025 to engage the body pins 3011 and compress theinfusion line 3210 against the inlet and/or outlet valves 3101, 3111without inordinate manual force exerted against the lever 3025.

The lever 3025, split carriage 3021 and door assembly 3021 are designedto maintain the occlusion of the infusion line 3210 at all times duringthe door 3020 opening and closing processes. The infusion line 3210 isoccluded by pressing the door 3020 against the body, before the slideoccluder 3200 is moved by the split carriage 3041 during closing. In theopening process, the slide occluder 3200 is moved first to block theinfusion line 3210 before the door 3020 is disengaged from the body andallows the infusion line 3210 to become decompressed.

The slotted rib 3025A and lever link 3035 allow the lever 3025 to rotateseveral degrees and begin engaging the body pins 3011 with the latchhooks 3025C without moving the split carriage 3041 when closing thelever 3025. Upon opening, the slotted rib 3025A and lever link 3035allow the lever 3025 to retract the split carriage 3041 and block theinfusion line 3201 before disengaging the body pins 3011 and releasingthe infusion line 3210 from the valves 3101, 3111. The lever link 3035mechanically connects the lever 3025 to the door split carriage 3041such that the lever 3025 only applies a tension force on the lever link3035. Limiting the force on the lever link 3035 to tension force removesthe need to ensure the lever link 3035 is buckle resistant, allowing thelever link 3035 to be lighter and smaller.

The rotation of the lever 3025 toward the door 3020 and body 3001compresses the infusion line 3210 between the platen 3022 and the valves3101, 3111 and plunger 3091, latches the door 3020 shut and moves theslide occluder 3200 to an open position. The lever link 3035 and theslotted rib 3025A and the geometry of the latch hook 3025C assure thatthe infusion line 3210 is compressed against the valves 3101, 3111before the slide occluder 3200 is moved to the open position when thelever 3025 is closed. The lever link 3035 and the slotted rib 3025A andthe geometry of the latch hook 3025C also assure that the slide occluder3200 is moved into the closed position before the infusion line 3210 isuncompressed against the valves 3101, 3111 when the lever 3025 isopened. This sequence of blocking flow through the infusion line 3210with one element before releasing the second element assures that theinfusion line 3210 is never in a free-flow state during the loading ofthe infusion line 3210 in the peristaltic pump 2990.

Alternatively, the door split carriage 3040 may be pulled out of thepump body 3001 by the lever 3025 that is connected to the door splitcarriage 3040 by two links 3036, 3037 as shown in FIG. 288. The firstlink 3036 fits over the split carriage pin 3040A and connects to thesecond link 3037 at hinge 3036A. The second link connects the first link3036 to the lever 3025 at pivot point 3025G. The two links 3036, 3037each have a flat 3036B, 3037B that limits the relative rotation of thelinks 3036, 3037 so that they never cross a center point and always foldtoward each other in the same direction. In the pictured embodiment, thelinks 3036, 3037 can only fold so that their mutual pivot point 3036Amoves away from the lever pivot 3025B as the lever 3025 closes. The twolinks 3036, 3037 allows the lever 3025 to rotate several degrees andbegin engaging the body pins 3011 with the latch hooks 3025C and occludethe infusion line 3210 against at least one of the valves 3101, 3111without moving the split carriage 3041. Once the two links 3036, 3037have folded closed, the rib 3025F contacts the door split carriage 3040.The rib 3025F pushes the split carriage 3041 into the pump body 3001 asthe lever 3025 completes its rotation toward the door assembly 3021.

Upon opening the lever 3025, or rotating the lever 3025 away from thedoor assembly 3021, the two links 3036, 3037 unfold and only begin toretract the split carriage 3041 after an initial lever 3025 rotation.During the second part of the lever 3025 rotation, the split carriage3041 withdraws from the pump body 3001 and moves slide occluder 3200,which blocks the infusion line 3210 before disengaging the body pins3011 and releasing the infusion line 3210 from the valves 3101, 3111.The infusion line 3210 is uncompressed during the third portion of thelever 3025 rotation.

Alternatively, the two links 3036, 3037 could be replaced with aflexible cable or wire, which pulls the split carriage 3041 out of thepump body 3001. The flexible cable may be attached to the door splitcarriage 3040 and to a fixed point on the lever 3025. The split carriage3041 is pushed into the pump body 3001 by the rib 3025F as the lever3025 rotates toward the pump body 3001.

FIG. 274 illustrates the peristaltic pump 2990 having L-shaped camfollowers 3090, 3100, 3110. The door 3020 is closed and the lever 3025latched as shown in FIG. 289. The split carriage 3041 has been partiallyslid through the door 3020 and into the body 3001. The movement of thesplit carriage 3041 moves the slide occluder 3200 into the pump body3001, while the infusion line 3210 is held in position. The movement ofthe slide occluder 3200 relative to the infusion line 3210 moves theinfusion line 3210 into the wide end 3200C of the slide occluder 3200allowing flow through the infusion line 3210.

FIGS. 290-293 illustrate four steps of closing the door 3020 of theperistaltic pump 2990 having L-shaped cam followers 3090, 3100, 3110. InFIG. 290, the door assembly 3021 is open and the infusion line 3210 andslide occluder 3200 are installed. In FIG. 291, the door assembly 3021is closed, the lever 3025 is open and the split carriage 3041 is fullyretracted, so the infusion line 3210 is blocked by the slide occluder3200. In FIG. 292, the lever 3025 is partially rotated toward the body3001 to a point where the split carriage 3041 has not moved and theslide occluder 3200 blocks the infusion line, but the latch hooks 3025Chave engaged the body pins 3011 and compressed the infusion line 3210between the door assembly 3021 and at least one of the valves 3101,3111. In FIG. 293, the lever 3025 is fully rotated toward the pump body3001 or closed. In FIG. 293, the slide carriage 3041 is fully insertedinto the pump body 3001, so that the infusion line 3210 is unblocked bythe slide occluder 3200 and the door 3021 is fully preloaded against thepump body 3001 including at least one of the valves 3101, 3111.

FIGS. 294-298 illustrate the elements of the door assembly 3021 and pumpbody 3001 and lever 3025 that together latch the door 3020 closed, andposition the door assembly 3021 parallel to the face of theupper-housing 3010 and compress the infusion line 3210 between theplaten 3022 and at least one of the valves 3101, 3111 and plunger 3091.The door assembly 3021 is positioned and pressed against the upperhousing 3010 without placing a load on the hinge pin 3012 or requiringclose tolerance on hinge pin 3012 and pivot holes 3020J, 3010F.

As described above and pictured in FIGS. 283, 287 the two latch hooks3025C engage the body pins 3011, which are mounted in the upper housing3010 tabs 3010B, when the door assembly 3021 has been rotated to contactthe upper housing 3012 and the lever 3025 is rotated toward the door3020. The latch hooks 3025C have tapered openings to assure engagementfor a broader range of initial positions between the door assembly 3021(FIG. 257) and the upper housing 3010 (FIG. 258). The opening in thelatch hook 3025C is shaped to pull the latch pin 3034 (FIG. 299) closerto the body pin 3011 as the lever 3025 (FIG. 257) is rotated. The latchpin 3034 (FIG. 299) is free to move within the door 3020 along slots3020C as the latch pin 3034 moves toward the body pin 3011 (FIG. 294).The slot structure 3020C on the top of the door 3020 in FIG. 294 isrepeated toward the bottom of the door 3020 in FIG. 295, where thesecond latch 3025C engages the latch pin 3034.

In FIG. 298, the movement of the latch pin 3034 toward the upper housing3010 deflects the door spring 3032 that is supported by the door 3020 ateach end of the door spring 3032A. The deflection of the door spring3032 generates a force that is applied to the door 3020 and directedtoward the upper housing 3010 and the pump body 3001. The pump body 3010includes protrusions or standoffs 3025H that contact the face of theupper housing 3010 in three or more places distributed around the valves3101, 3111 and plunger 3091 (FIG. 260). In one embodiment, the standoffs3025H are also positioned within and equal distance to the contact areabetween the door spring 3032 and the door 3020 so that the spring forceis equally distributed to each standoff 3025H. In one embodiment asshown in FIG. 296, four standoffs 3020H are located around the platen3022, near where the valves 3101, 3111 (FIG. 260) contact the infusionline 3210. The pivot holes 3020 in the door 3020 are slightly oversizedfor the hinge pin 3012 (FIG. 295), which allows the door 3020 to rest onthe standoffs 3025H without being constrained by the hinge pin 3012.

FIG. 297 shows the cross-section through the latch pin and includes thelatches 3025C fully engaging body pins 3011. In one embodiment, the bodypins 3011 include a plain bearing 3011A to reduce wear and friction. Theplain bearing 3011A is tube of hard material that can rotate on the bodypin 3011 to reduce wear on the latch hooks 3025C. The latch pin 3034passes through the lever pivot holes 3025B and is free to move in theslots 3020C and deflect the door spring 3032. In FIG. 297, the plunger3091 is in a position to compress the infusion line 3210 against theplaten 3022. The force of the deflected door spring 3032 supplies theforce to compress the infusion line 3210 from the platen 3022 side,while the plunger elastic element 3094 (FIG. 267) supplies the force onthe plunger 3091 side.

FIG. 298 shows the cross section across the middle of the door spring3032 and perpendicular to the latch pin 3034. The deflection of the doorspring 3032 is evident between the latch pin 3034 and an edge 3020F ateach end of the door spring 3032 and of the spring cutout 3020G. FIG.296 presents an embodiment where the standoffs 3020H are located betweenand equal distant to the locations where the door spring 3032 contactsthe door 3020.

In one embodiment shown in FIG. 299-300, one of the latch hooks 3025Cmay comprise detents 3025G, 3025J and a spring pin 3027 or ball toengage the detents 3025G, 3025J. FIG. 299 illustrates the lever 3025fully closed against the door 3020. The latch hook 3025C includes afirst detent 3025G that is engaged by a spring pin 3027. The spring pin3027 is mounted in the door 3020 at such a position that it engages thefirst detent 3025G when lever 3025 is closed.

FIG. 300 illustrates the lever 3025 fully opened relative to door 3020and the door split carriage 3040 retracted. The spring pin 3027 engagesa second detent 3025J when the door 3020 is in the fully open position.In some embodiments, the detents 3025G, 3025J in the latch hooks 3025Cmay allow the lever 3025 to hold one or more positions relative to thedoor 3020.

FIG. 301 illustrates a detection lever 3150 displaced by the slideoccluder 3200, when the door assembly 3021 and the lever 3025 (FIG. 265)are fully are closed. The detection lever 3150 rotates on a pin 3151that is attached to the upper housing 3010 and swings through a slot3045F (FIG. 285) in the body split carriage 3045. If a slide occluder3200 is present in the split carriage 3041 when the door 3020 is closed,the slide occluder 3200 will deflect the detection lever 3150 upwardtoward the main PCB 3002. A sensor 3152 on the main PCB 3002 will detectthe nearness of a magnet 3150A on the detection lever 3150. Thedetection lever 3150, magnet 3150A and sensor 3152 may be designed toonly detect a specific slide occluder 3200 geometry. Other slideoccluders 3200 or slide occluder 3200 shapes may not deflect thedetection lever 3150 enough for the sensor 3152 to detect the magnet3150A or cause the detection lever 3150 to contact the main PCB 3002 andprevent the full insertion of the split carriage 3041 and closing of thelever 3025. A controller may only allow peristaltic pump 2990 operationwhen the sensor 3152 detects the displaced detection lever 3150indicating that the appropriate slide occluder 3200 is present.

FIG. 302 illustrates a latch hook detection slide 3160 displaced by thelatch hook 3025C, when the door assembly 3021 and the lever 3025 arefully closed. The latch hook detection slide 3160 includes one or moreslots 3160A that guide it past screws or posts on mounted in the upperhousing 3010. A spring 3164 returns latch hook detection slide 3160 to anon-displaced position, when the latch hook 3025C is engaging the bodypin 3011. The latch hook detection slide 3160 includes at least onemagnet that is located so that a sensor 3163 mounted on the main PCB3001 will detect it presence only when the detection slide 3160 is fullydisplaced. In one embodiment, the latch hook detection slide 3160 mayinclude a second magnet 3162 that is detected by the sensor 3163 onlywhen the latch hook detection slide 3160 is fully retracted. Acontroller may only allow peristaltic pump 2990 operation when thesensor 3163 detects the displaced latch hook detection slide 3160indicating that the lever 3025 is fully closed.

FIGS. 303-310 show various views related to a system 3200. FIG. 303shows a system 3200 that includes several pumps 3201, 3202, and 3203.The pumps 3201, 3202, 3203 can be coupled together to form a group ofpumps that are connectable to a pole 3208. The system 3200 includes twosyringe pumps 3201, 3202 and a peristaltic pump 3203; however, othercombinations of various medical devices may be employed.

Each of the pumps 3201, 3202, 3203 includes a touch screen 3204 whichmay be used to control the pumps 3201, 3202, 3203. One of the pumps'(e.g., 3201, 3202, 3203) touch screens 3204 may also be used tocoordinate operation of all of the pumps 3201, 3202, 3203 and/or tocontrol the one or more of the other pumps 3201, 3202, 3203.

The pumps 3201, 3202, and 3203 are daisy chained together such that theyare in electrical communication with each other. Additionally oralternatively, the pumps 3201, 3202, and/or 3203 may share power witheach other or among each other. For example, one of the pumps 3201,3202, and/or 3203 may include an AC/DC converter that converts ACelectrical power to DC power suitable to power the other pumps 3201,3202, 3203.

Within the system 3200, the pumps 3201, 3202, and 3203 are stackedtogether using respective Z-frames 3207. Each of the Z-frames 3207includes a lower portion 3206 and an upper portion 3205. A lower portion3206 of one Z-frame 3207 (e.g., the lower portion 3206 of the pump 3201)can engage an upper portion 3205 of another Z-frame 3207 (e.g., theupper portion 3205 of the Z-frame 3207 of the pump 3202).

A clamp 3209 may be coupled to one of the pumps 3201, 3202, 3203 (e.g.,the pump 3202 as shown in FIG. 304). That is, the clamp 3209 may becoupled to any one of the pumps 3201, 3202, and/or 3203. The clamp 3209is attachable to the back of any one of the pumps 3201, 3202, and/or3203. As is easily seen in FIG. 306, each of the pumps 3201, 3202, 3203includes an upper attachment member 3210 and a lower attachment member3211. A clamp adapter 3212 facilitates the attachment of the clamp 3209to the pump 3202 via a respective pump's (e.g., 3201, 3202, or 3203)upper attachment member 3210 and lower attachment member 3211. In someembodiments, the clamp adapter 3212 may be integral with the clamp 3209.

FIG. 307 shows a close-up view of a portion of an interface of a clamp(i.e., the clamp adapter 3212) that is attachable to the pump 3202 (orto pumps 3201 or 3203) shown in FIGS. 304-306 in accordance with anembodiment of the present disclosure. The clamp adapter 3212 includes ahole 3213 in which a lower attachment member 3211 (see FIG. 306) may beattached. That is, the lower attachment member 3211, a curved hook-likeprotrusion, may be inserted into the hole 3213 and thereafter rotated tosecure the lower attachment member 3211 therein.

As is easily seen in FIG. 308, the clamp adapter 3212 also includes alatch 3214. The latch 3214 is pivotally mounted to the clamp adapter3212 via pivots 3216. The latch 3214 may be spring biased via springs3218 that are coupled to the hooks 3220. The stop members 3219 preventthe latch 3214 from pivoting beyond a predetermined amount. After thehole 3213 is positioned on the lower attachment member 3211, the clampadapter 3212 may be rotated to bring the latch 3214 towards the upperattachment member 3210 such that the latch 3214 is compressed down bythe upper attachment member 3210 until the protrusion 3215 snaps into acomplementary space of the upper attachment member 3210. The hooks 3220help secure the clamp adapter 3212 to the pump 3202.

Each of the Z-frames 3207 for each of the pumps 3201, 3202, 3203includes a recessed portion 3223 on its upper portion 3205 (see FIG.306) and each pump 3201, 3202, 3203 includes a protrusion 3224 (see FIG.309). A protrusion 3224 of one pumps (e.g., pumps 3201, 3202, or 3203)may engage a recessed portion 3223 of another Z-frame to enable thepumps 3201, 3202, 3203 to be stacked on top of each other. Each of thepumps 3201, 3202, 3203 includes a latch engagement member 3221 thatallows another one of the pumps 3201, 3202, 3203 to be attached theretovia a latch 3222 (see FIG. 309). The latch 3222 may include a smallspring loaded flange that can “snap” into the space formed under thelatch engagement member 3221. The latch 3222 may be pivotally coupled tothe lower portion 3206 of the Z-frame 3207.

As is seen FIG. 304, the latch 3222 of the Z-frame of pump 3201 may bepulled to withdraw a portion of the latch 3222 out of the space underthe latch engagement member 3221 of the pump 3202. Thereafter, the pump3201 may be rotated to pull the protrusion 3224 of the pump 3201 out ofthe recessed portion 3223 of the Z-frame of pump 3202 such that the pump3201 may be removed from the stack of pumps 3202, 3203 (see FIG. 305).

Each of the pumps 3201, 3202, 3203 includes a top connector 3225 (seeFIG. 310) and a bottom connector 3226 (see FIG. 309). The connectors3225 and 3226 allow the stacked pumps 3201, 3202, and 3203 tocommunication between each other and/or to provide power to each other.For example, if the battery of the middle pump 3202 (see FIG. 303)fails, then the top pump 3201 and/or the bottom pump 3203 may providepower to the middle pump 3202 as a reserve while one or more of thepumps 3201, 3202, 3203 is audibly alarming.

An example embodiment of the graphic user interface (hereafter GUI) 3300is shown in FIG. 311. The GUI 3300 enables a user to modify the way thatan agent may be infused by customizing various programming options. Forpurposes of example, the GUI 3300 detailed as follows uses a screen 3204which is a touch screen as a means of interaction with a user. In otherembodiments, the means of interaction with a user may be different. Forinstance, alternate embodiments may comprise user depressible buttons orrotatable dials, audible commands, etc. In other embodiments, the screen3204 may be any electronic visual display such as a, liquid crystaldisplay, L.E.D. display, plasma display, etc.

As detailed in the preceding paragraph, the GUI 3300 is displayed on thescreen of the pumps 3203. All of the pumps 3201, 3202, 3203 may havetheir own individual screen 3204 as shown in FIGS. 303-305. Inarrangements where one of the pumps 3201, 3202, 3203 is being used tocontrol all of the pumps 3201, 3202, 3203, only the master pump mayrequire a screen 3204. As shown, the pump is seated in a Z-frame 3207.As shown, the GUI 3300 may display a number of interface fields 3250.The interface fields 3250 may display various information about the pumpor infusion status, the medication, etc. In some embodiments, theinterface fields 3250 on the GUI 3300 may be touched, tapped, etc. tonavigate to different menus, expand an interface field 3250, input data,and the like. The interface fields 3250 displayed on the GUI 3300 maychange from menu to menu.

The GUI 3300 may also have a number of virtual buttons. In thenon-limiting example embodiment in FIG. 311 the display has a virtualpower button 3260, a virtual start button 3262, and a virtual stopbutton 3264. The virtual power button 3260 may turn the pump 3201, 3202,3203 on or off. The virtual start button 3262 may start an infusion. Thevirtual stop button 3264 may pause or stop an infusion. The virtualbuttons may be activated by a user's touch, tap, double tap, or thelike. Different menus of the GUI 3300 may comprise other virtualbuttons. The virtual buttons may be skeuomorphic to make their functionsmore immediately understandable or recognizable. For example, thevirtual stop button 3264 may resemble a stop sign as shown in FIG. 305.In alternate embodiments, the names, shapes, functions, number, etc. ofthe virtual buttons may differ.

As shown in the example embodiment in FIG. 312, the interface fields3250 of the GUI 3300 (see FIG. 311) may display a number of differentprogramming parameter input fields. For the GUI 3300 to display theparameter input fields, a user may be required to navigate through oneor a number of menus. Additionally, it may be necessary for the user toenter a password before the user may manipulate any of the parameterinput fields.

In FIG. 312, a medication parameter input field 3302, in container drugamount parameter input field 3304, total volume in container parameterinput field 3306, concentration parameter input field 3308, doseparameter input field 3310, volume flow rate (hereafter abbreviated asrate) parameter input field 3312, volume to be infused (hereafter VTBI)parameter input field 3314, and time parameter input field 3316 aredisplayed. The parameters, number of parameters, names of theparameters, etc. may differ in alternate embodiments. In the exampleembodiment, the parameter input fields are graphically displayed boxeswhich are substantially rectangular with rounded corners. In otherembodiments, the shape and size of the parameter input fields maydiffer.

In the example embodiment, the GUI 3300 is designed to be intuitive andflexible. A user may choose to populate a combination of parameter inputfields which are simplest or most convenient for the user. In someembodiments, the parameter input fields left vacant by the user may becalculated automatically and displayed by the GUI 3300 as long as thevacant fields do not operate independent of populated parameter inputfields and enough information can be gleaned from the populated fieldsto calculate the vacant field or fields. Throughout FIGS. 312-316 fieldsdependent upon on another are tied together by curved double-tippedarrows.

The medication parameter input field 3302 may be the parameter inputfield in which a user sets the type of infusate agent to be infused. Inthe example embodiment, the medication parameter input field 3302 hasbeen populated and the infusate agent has been defined as “0.9% NORMALSALINE”. As shown, after the specific infusate has been set, the GUI3300 may populate the medication parameter input field 3302 bydisplaying the name of the specific infusate in the medication parameterinput field 3302.

To set the specific infusate agent to be infused, a user may touch themedication parameter input field 3302 on the GUI 3300. In someembodiments, this may cull up a list of different possible infusates.The user may browse through the list until the desired infusate islocated. In other embodiments, touching the in medication parameterinput field 3302 may cull up a virtual keyboard. The user may then typethe correct infusate on the virtual keyboard. In some embodiments, theuser may only need to type only a few letters of the infusate on thevirtual keyboard before the GUI 3300 displays a number of suggestions.For example, after typing “NORE” the GUI 3300 may suggest“NOREPINEPHRINE”. After locating the correct infusate, the user may berequired to perform an action such as, but not limited to, tapping,double tapping, or touching and dragging the infusate. After therequired action has been completed by the user, the infusate may bedisplayed by the GUI 3300 in the medication parameter input field 3302.For another detailed description of another example means of infusateselection see FIG. 322.

In the example embodiment in FIG. 312, the parameter input fields havebeen arranged by a user to perform a volume based infusion (for instancemL, mL/hr, etc.). Consequentially, the in container drug amountparameter input field 3304 and total volume in container parameter inputfield 3306 have been left unpopulated. The concentration parameter inputfield 3308 and dose parameter input field 3310 have also been leftunpopulated. In some embodiments, the in container drug amount parameterinput field 3304, total volume in container parameter input field 3306,concentration parameter input field 3308, and dose parameter input field3310 may be locked, grayed out, or not displayed on the GUI 3300 whensuch an infusion has been selected. The in container drug amountparameter input field 3304, total volume in container parameter inputfield 3306, concentration parameter input field 3308, and dose parameterinput field 3310 will be further elaborated upon in subsequentparagraphs.

When the GUI 3300 is being used to program a volume base infusion, therate parameter input field 3312, VTBI parameter input field 3314, andtime parameter input field 3316 do not operate independent of oneanother. A user may only be required to define any two of the rateparameter input field 3312, VTBI parameter input field 3314, and timeparameter input field 3316. The two parameters defined by a user may bethe most convenient parameters for a user to set. The parameter leftvacant by the user may be calculated automatically and displayed by theGUI 3300. For instance, if a user populates the rate parameter inputfield 3312 with a value of 125 mL/hr (as shown), and populates the VTBIparameter input field 3314 with a value of 1000 mL (as shown) the timeparameter input field 3316 value may be calculated by dividing the valuein the VTBI parameter input field 3314 by the value in the rateparameter input field 3312. In the example embodiment shown in FIG. 312,the quotient of the above calculation, 8 hrs and 0 min, is correctlypopulated by the GUI 3300 into the time parameter input field 3316.

For a user to populate the rate parameter input field 3312, VTBIparameter input field 3314, and time parameter input field 3316 the usermay touch or tap the desired parameter input field on the GUI 3300. Insome embodiments, this may cull up a number pad with a range or number,such as 0-9 displayed as individual selectable virtual buttons. A usermay be required to input the parameter by individually tapping, doubletapping, touching and dragging, etc. the desired numbers. Once thedesired value has been input by a user, a user may be required to tap,double tap, etc. a virtual “confirm”, “enter”, etc. button to populatethe field. For another detailed description of another example way ofdefining numerical values see FIG. 322.

FIG. 313 shows a scenario in which the infusion parameters beingprogrammed are not those of a volume based infusion. In FIG. 313, theinfusion profile is that of a continuous volume/time dose rate. In theexample embodiment shown in FIG. 313, all of the parameter input fieldshave been populated. As shown, the medication parameter input field 3302on the GUI 3300 has been populated with “HEPARIN” as the definedinfusate. As shown, the in container drug amount parameter input field3304, total volume in container input field 3306, and concentrationparameter input field 3308 are populated in FIG. 313. Additionally,since a volume/time infusion is being programmed the dose parameterinput field 3310 shown in FIG. 312 has been replaced with a dose rateparameter input field 3318.

The in container drug amount parameter input field 3304 is a two partfield in the example embodiment shown in FIG. 313. In the exampleembodiment in FIG. 313 the left field of the in container drug amountparameter input field 3304 is a field which may be populated with anumeric value. The numeric value may defined by the user in the samemanner as a user may define values in the rate parameter input field3312, VTBI parameter input field 3314, and time parameter input field3316. In the example embodiment shown in FIG. 313, the numeric valuedisplayed by the GUI 3300 in the in left field of the in container drugamount parameter input field 3304 is “25,000”.

The parameter defined by the right field of the in container drug amountparameter input field 3304 is the unit of measure. To define the rightof the in container drug amount parameter input field 3304, a user maytouch the in container drug amount parameter input field 3304 on the GUI3300. In some embodiments, this may cull up a list of acceptablepossible units of measure. In such embodiments, the desired unit ofmeasure may be defined by a user in the same manner as a user may definethe correct infusate. In other embodiments, touching the in containerdrug amount parameter input field 3304 may cull up a virtual keyboard.The user may then type the correct unit of measure on the virtualkeyboard. In some embodiments the user may be required to tap, doubletap, etc. a virtual “confirm”, “enter”, etc. button to populate the leftfield of the in container drug amount parameter input field 3304.

In some embodiments, including the embodiment shown in FIG. 313, theright field of the in container drug amount parameter input field 3304may have one or more acceptable values with may be dependent on theparameter input into one or more other parameter input fields. In theexample embodiment, the meaning of the unit of measure “UNITS” maydiffer depending on the infusate set in the medication parameter inputfield. The GUI 3300 may also automatically convert the value and unit ofmeasure in respectively the left field and right field of the incontainer drug amount parameter input field 3304 to a metric equivalentif a user inputs a non-metric unit of measure in the right field of thein container drug amount parameter input field 3304.

The total volume in container parameter input field 3306 may bepopulated by a numeric value which defines the total volume of acontainer. In some embodiments, the GUI 3300 may automatically populatethe total volume in container parameter input field 3306 based on datagenerated by one or more sensors. In other embodiments, the total volumein container parameter input field 3306 may be manually input by a user.The numeric value may defined by the user in the same manner as a usermay define values in the rate parameter input field 3312, VTBI parameterinput field 3314, and time parameter input field 3316. In the exampleembodiment shown in FIG. 313 the total volume in container parameterinput field 3306 has been populated with the value “250” mL. The totalvolume in container parameter input field 3306 may be restricted to aunit of measure such as mL as shown.

The concentration parameter input field 3308 is a two part field similarto the in container drug amount parameter input field 3304. In theexample embodiment in FIG. 313 the left field of the concentrationparameter input field 3308 is a field which may be populated with anumeric value. The numeric value may defined by the user in the samemanner as a user may define values in the rate parameter input field3312, VTBI parameter input field 3314, and time parameter input field3316. In the example embodiment shown in FIG. 313, the numeric valuedisplayed by the GUI 3300 in the in left field of the concentrationparameter input field 3308 is “100”.

The parameter defined by the right field of the concentration parameterinput field 3308 is a unit of measure/volume. To define the right fieldof the concentration parameter input field 3308, a user may touch theconcentration parameter input field 3308 on the GUI 3300. In someembodiments, this may cull up a list of acceptable possible units ofmeasure. In such embodiments, the desired unit of measure may be definedby a user in the same manner as a user may define the correct infusate.In other embodiments, touching the concentration parameter input field3308 may cull up a virtual keyboard. The user may then type the correctunit of measure on the virtual keyboard. In some embodiments the usermay be required to tap, double tap, etc. a virtual “confirm”, “enter”,etc. button to store the selection and move on to a list of acceptablevolume measurements. The desired volume measurement may be defined by auser in the same manner as a user may define the correct infusate. Inthe example embodiment shown in FIG. 313 the right field of theconcentration parameter input field 3308 is populated with the unit ofmeasure/volume “UNITS/mL”.

The in container drug amount parameter input field 3304, total volume incontainer input field 3306, and concentration parameter input field 3308are not independent of one another. As such, a user may only be requiredto define any two of the in container drug amount parameter input field3304, total volume in container input field 3306, and concentrationparameter input field 3308. For instance, if a user were to populate theconcentration parameter input field 3308 and the total volume incontainer parameter input field 3306, the in container drug amountparameter input field may be automatically calculated and populated onthe GUI 3300.

Since the GUI 3300 in FIG. 313 is being programmed for a continuousvolume/time dose, the dose rate parameter input field 3318 has beenpopulated. The user may define the rate at which the infusate is infusedby populating the dose rate parameter input field 3318. In the exampleembodiment in FIG. 313, the dose rate parameter input field 3318 is atwo part field similar to the in container drug amount parameter inputfield 3304 and concentration parameter input field 3308 described above.A numeric value may defined in the left field of the dose rate parameterinput field 3318 by the user in the same manner as a user may definevalues in the rate parameter input field 3312. In the example embodimentin FIG. 313, the left field of the dose rate parameter input field 3318has been populated with the value “1000”.

The right field of the dose rate parameter input field 3318 may define aunit of measure/time. To define the right field of the dose rateparameter input field 3318, a user may touch the dose rate parameterinput field 3318 on the GUI 3300. In some embodiments, this may cull upa list of acceptable possible units of measure. In such embodiments, thedesired unit of measure may be defined by a user in the same manner as auser may define the correct infusate. In other embodiments, touching thedose rate parameter input field 3304 may cull up a virtual keyboard. Theuser may then type the correct unit of measure on the virtual keyboard.In some embodiments the user may be required to tap, double tap, etc. avirtual “confirm”, “enter”, etc. button to store the selection and moveon to a list of acceptable time measurements. The desired timemeasurement may be defined by a user in the same manner as a user maydefine the correct infusate. In the example embodiment shown in FIG. 313the right field of the dose rate parameter input field 3318 is populatedwith the unit of measure/time “UNITS/hr”.

In the example embodiment, the dose rate parameter input field 3318 andthe rate parameter input field 3312 are not independent of one another.After a user populates the dose rate parameter input field 3318 or therate parameter input field 3312, the parameter input field left vacantby the user may be calculated automatically and displayed by the GUI3300 as long as the concentration parameter input field 3308 has beendefined. In the example embodiment shown in FIG. 313, the rate parameterinput field 3312 has been populated with an infusate flow rate of “10mL/hr”. The dose rate parameter input field 3318 has been populated with“1000” “UNITS/hr”.

In the example embodiment shown in FIG. 313 the VTBI parameter inputfield 3314 and time parameter input field 3316 have also been populated.The VTBI parameter input field 3314 and time parameter input field 3316may be populated by a user in the same manner described in relation toFIG. 306. When the GUI 3300 is being programmed to a continuousvolume/time dose rate infusion, the VTBI parameter input field 3314 andthe time parameter input field 3316 are dependent on one another. A usermay only need to populate one of the VTBI parameter input field 3314 orthe time parameter input field 3316. The field left vacant by the usermay be calculated automatically and displayed on the GUI 3300.

FIG. 314 shows a scenario in which the infusion parameters beingprogrammed are those of a drug amount based infusion herein referred toas an intermittent infusion. In the example embodiment shown in FIG.314, all of the parameter input fields have been populated. As shown,the medication parameter input field 3302 on the GUI 3300 has beenpopulated with the antibiotic “VANCOMYCIN” as the defined infusate.

As shown, the in container drug amount parameter input field 3304, totalvolume in container input field 3306, and concentration parameter inputfield 3308 are laid out the same as in FIG. 314. In the exampleembodiment in FIG. 308, the left field of the in container drug amountparameter input field 3304 has been populated with “1”. The right fieldof the in container drug amount parameter input field 3304 has beenpopulated with “g”. Thus the total amount of Vancomycin in the containerhas been defined as one gram. The total volume in container parameterinput field 3306 has been populated with “250” ml. The left field of theconcentration parameter input field 3308 has been populated with “4.0”.The right field of the concentration parameter input field has beenpopulated with “mg/mL”.

As mentioned in relation to other possible types of infusions which auser may be capable of programming through the GUI 3300, the incontainer drug amount parameter input field 3304, total volume incontainer input field 3306, and concentration parameter input field 3308are dependent upon each other. As above, this is indicated by the curveddouble arrows connecting the parameter input field names. By populatingany two of these parameters, the third parameter may be automaticallycalculated and displayed on the correct parameter input field on the GUI3300.

In the example embodiment in FIG. 314, the dose parameter input field3310 has been populated. As shown, the dose parameter input field 3310comprises a right and left field. A numeric value may defined in theright field of the dose parameter input field 3310 by the user in thesame manner as a user may define values for other parameter input fieldswhich define numeric values. In the example embodiment in FIG. 314, theleft field of the dose parameter input field 3310 has been populatedwith the value “1000”.

The right field of the dose parameter input field 3310 may define a unitof mass measurement. To define the right field of the dose parameterinput field 3310, a user may touch the dose parameter input field 3310on the GUI 3300. In some embodiments, this may cull up a list ofacceptable possible units of measure. In such embodiments, the desiredunit of measure may be defined by a user in the same manner as a usermay define the correct infusate. In other embodiments, touching the doseparameter input field 3310 may cull up a virtual keyboard. The user maythen type the correct unit of measure on the virtual keyboard. In someembodiments the user may be required to tap, double tap, slide, etc. avirtual “confirm”, “enter”, etc. button to store the selection and moveon to a list of acceptable mass measurements. The desired massmeasurement may be defined by a user in the same manner as a user maydefine the correct infusate. In the example embodiment shown in FIG. 314the right field of the dose parameter input field 3310 is populated withthe unit of measurement “mg”.

As shown, the rate parameter input field 3312, VTBI parameter inputfield 3314, and the time parameter input field 3316 have been populated.As shown, the rate parameter input field 3312 has been populated with“125” mL/hr. The VTBI parameter input field 3314 has been defined as“250” mL. The time parameter input field 3316 has been defined as “2”hrs “00” min.

The user may not need to individually define each of the dose parameterinput field 3310, rate parameter input field 3312, VTBI parameter inputfield 3314, and the time parameter input field 3316. As indicated by thecurved double arrows, the dose parameter input field 3310 and the VTBIparameter input field 3314 are dependent upon each other. Input of onevalue may allow the other value to be automatically calculated anddisplayed by the GUI 3300. The rate parameter input field 3312 and thetime parameter input field 3316 are also dependent upon each other. Theuser may need to only define one value and then allow the non-definedvalue to be automatically calculated and displayed on the GUI 3300. Insome embodiments, the rate parameter input field 3312, VTBI parameterinput field 3314, and the time parameter input field 3316 may be lockedon the GUI 3300 until the in container drug amount parameter input field3304, total volume in container parameter input field 3306 andconcentration parameter input field 3308 have been defined. These fieldsmay be locked because automatic calculation of the rate parameter inputfield 3312, VTBI parameter input field 3314, and the time parameterinput field 3316 is dependent upon values in the in container drugamount parameter input field 3304, total volume in container parameterinput field 3306 and concentration parameter input field 3308.

In scenarios where an infusate may require a body weight based dosage, aweight parameter input field 3320 may also be displayed on the GUI 3300.The example GUI 3300 shown on FIG. 315 has been arranged such that auser may program a body weight based dosage. The parameter input fieldsmay be defined by a user as detailed in the above discussion. In theexample embodiment, the infusate in the medication parameter input field3302 has been defined as “DOPAMINE”. The left field of the in containerdrug amount parameter input field 3304 has been defined as “400”. Theright field of the in container drug amount parameter input field 3304has been defined as “mg”. The total volume in container parameter inputfield 3306 has been defined as “250” ml. The left field of theconcentration parameter input field 3308 has been defined as “1.6”. Theright field of the concentration parameter input field 3308 has beendefined as “mg/mL”. The weight parameter input field 3320 has beendefined as “90” kg. The left field of the dose rater parameter inputfield 3318 has been defined as “5.0”. The right field of the dose rateparameter input field 3318 has been defined as “mcg/kg/min”. The rateparameter input field 3312 has been defined as “16.9” mL/hr. The VTBIparameter input field 3314 has been defined as “250” mL. The timeparameter input field 3316 has been defined as “14” hrs “48” min.

To define the weight parameter input field 3320, a user may touch or tapthe weight parameter input field 3320 on the GUI 3300. In someembodiments, this may cull up a number pad with a range of numbers, suchas 0-9 displayed as individual selectable virtual buttons. A user may berequired to input the parameter by individually tapping, double tapping,touching and dragging, etc. the desired numbers. Once the desired valuehas been input by a user, a user may be required to tap, double tap,etc. a virtual “confirm”, “enter”, etc. button to populate the field.

As indicated by the curved double arrows, some parameter input fieldsdisplayed on the GUI 3300 may be dependent upon each other. As inprevious examples, the in container drug amount parameter input field3304, total volume in container parameter input field 3306, andconcentration parameter input field 3308 may be dependent upon eachother. In FIG. 315, the weight parameter input field 3320, dose raterparameter input field 3318, rate parameter input field 3312, VTBIparameter input field 3314, and the time parameter input field 3316 areall dependent upon each other. When enough information has been definedby the user in these parameter input fields, the parameter input fieldsnot populated by the user may be automatically calculated and displayedon the GUI 3300.

In some embodiments, a user may be required to define a specificparameter input field even if enough information has been defined toautomatically calculate the field. This may improve safety of use bypresenting more opportunities for user input errors to be caught. If avalue entered by a user is not compatible with already defined values,the GUI 3300 may display an alert or alarm message soliciting the userto double check values that the user has entered.

In some scenarios the delivery of infusate may be informed by the bodysurface area (BSA) of a patient. In FIG. 316, the GUI 3300 has been setup for a body surface area based infusion. As shown, a BSA parameterinput field 3322 may be displayed on the GUI 3300. The parameter inputfields may be defined by a user as detailed in the above discussion. Inthe example embodiment, the infusate in the medication parameter inputfield 3302 has been defined as “FLUOROURACIL”. The left field of the incontainer drug amount parameter input field 3304 has been defined as“1700”. The right field of the in container drug amount parameter inputfield 3304 has been defined as “mg”. The total volume in containerparameter input field 3306 has been defined as “500” ml. The left fieldof the concentration parameter input field 3308 has been defined as“3.4”. The right field of the concentration parameter input field 3308has been defined as “mg/mL”. The BSA parameter input field 3320 has beendefined as “1.7” m². The left field of the dose rate parameter inputfield 3318 has been defined as “1000”. The right field of the dose rateparameter input field 3318 has been defined as “mg/m2/day”. The rateparameter input field 3312 has been defined as “20.8” mL/hr. The VTBIparameter input field 3314 has been defined as “500” mL. The timeparameter input field 3316 has been defined as “24” hrs “00” min. Thedependent parameter input fields are the same as in FIG. 309 with theexception that the BSA parameter input field 3322 has taken the place ofthe weight parameter input field 3320.

To populate the BSA parameter input field 3322, the user may touch ortap the BSA parameter input field 3322 on the GUI 3300. In someembodiments, this may cull up a number pad with a range of numbers, suchas 0-9 displayed as individual selectable virtual buttons. In someembodiments, the number pad and any of the number pads detailed abovemay also feature symbols such as a decimal point. A user may be requiredto input the parameter by individually tapping, double tapping, touchingand dragging, etc. the desired numbers. Once the desired value has beeninput by a user, a user may be required to tap, double tap, etc. avirtual “confirm”, “enter”, etc. button to populate the field.

In some embodiments, a patient's BSA may be automatically calculated anddisplayed on the GUI 3300. In such embodiments, the GUI 3300 may querythe user for information about the patient when a user touches, taps,etc. the BSA parameter input field 3322. For example, the user may beasked to define a patient's height and body weight. After the userdefines these values they may be run through a suitable formula to findthe patient's BSA. The calculated BSA may then be used to populate theBSA parameter input field 3322 on the GUI 3300.

In operation, the values displayed in the parameter input fields maychange throughout the course of a programmed infusion to reflect thecurrent state of the infusion. For example, as the infusate is infusedto a patient, the values displayed by the GUI 3300 in the in containerdrug amount parameter input field 3304 and total volume in containerparameter input field 3306 may decline to reflect the volume of theremaining contents of the container. Additionally, the values in theVTBI parameter input field 3314 and time parameter input field 3316 mayalso decline as infusate is infused to the patient.

FIG. 317 is an example rate over time graph detailing the one behavioralconfiguration of a pump 3201, 3202, 3203 (see FIG. 303) over the courseof an infusion. The graph in FIG. 317 details an example behavioralconfiguration of a pump 3201, 3202, 3203 where the infusion is acontinuous infusion (an infusion with a dose rate). As shown, the graphin FIG. 317 begins at the initiation of infusion. As shown, the infusionis administered at a constant rate for a period of time. As the infusionprogresses, the amount of infusate remaining is depleted. When theamount of infusate remaining reaches a pre-determined threshold, an“INFUSION NEAR END ALERT” may be triggered. The “INFUSION NEAR ENDALERT” may be in the form of a message on the GUI 3300 and may beaccompanied by flashing lights, and audible noises such as a series ofbeeps. The “INFUSION NEAR END ALERT” allows time for the care giver andpharmacy to prepare materials to continue the infusion if necessary. Asshown, the infusion rate may not change over the “INFUSION NEAR ENDALERT TIME”.

When the pump 3201, 3202, 3203 (see FIG. 303) has infused the VTBI to apatient a “VTBI ZERO ALERT” may be triggered. The “VTBI ZERO ALERT” maybe in the form of a message on the GUI 3300 and may be accompanied byflashing lights and audible noises such as beeps. As shown, the “VTBIZERO ALERT” causes the pump to switch to a keep-vein-open (hereafterKVO) rate until a new infusate container may be put in place. The KVOrate is a low infusion rate (for example 5-25 mL/hr). The rate is set tokeep the infusion site patent until a new infusion may be started. TheKVO rate is configurable by the group (elaborated upon later) ormedication and can be modified on the pump 3201, 3202, 3203. The KVOrate is not allowed to exceed the continuous infusion rate. When the KVOrate can no longer be sustained and air reaches the pumping channel an“AIR-IN-LINE ALERT” may be triggered. When the “AIR-IN-LINE-ALERT” istriggered, all infusion may stop. The “AIR-IN-LINE ALERT” may be in theform of a message on the GUI 3300 and may be accompanied by flashinglights and audible noises such as beeps.

FIG. 318 shows another example rate over time graph detailing onebehavioral configuration of a pump 3201, 3202, 3203 (see FIG. 303) overthe course of an infusion. The graph in FIG. 318 details an examplebehavioral configuration of a pump 3201, 3202, 3203 where the infusionis a continuous infusion (an infusion with a dose rate). The alerts inthe graph shown in FIG. 318 are the same as the alerts shown in thegraph in FIG. 317. The conditions which propagate the alerts are alsothe same. The rate, however, remains constant throughout the entiregraph until the “AIR-IN-LINE ALERT” is triggered and the infusion isstopped. Configuring the pump to continue infusion at a constant ratemay be desirable in situations where the infusate is a drug with a shorthalf-life. By continuing infusion at a constant rate, it is ensured thatthe blood plasma concentration of the drug remains at therapeuticallyeffective levels.

The pump 3201, 3202, 3203 (see FIG. 303) may also be used to deliver aprimary or secondary intermittent infusion. During an intermittentinfusion, an amount of a drug (dose) is administered to a patient asopposed to a continuous infusion where the drug is given at a specifieddose rate (amount/time). An intermittent infusion is also delivered overa defined period of time, however, the time period and dose areindependent of one another. The previously described FIG. 313 shows asetup of the GUI 3300 for a continuous infusion. The previouslydescribed FIG. 314 shows a setup of the GUI 3300 for an intermittentinfusion.

FIG. 319 is an example rate over time graph detailing the one behavioralconfiguration of a pump 3201, 3202, 3203 (see FIG. 303) over the courseof an intermittent infusion. As shown, the intermittent infusion isgiven at a constant rate until all infusate programmed for theintermittent infusion has been depleted. In the example behavioralconfiguration, the pump 3201, 3202, 3203 has been programmed to issue a“VTBI ZERO ALERT” and stop the infusion when all the infusate has beendispensed. In this configuration, the user may be required to manuallyclear the alert before another infusion may be started or resumed.

Other configurations may cause a pump 3201, 3202, 3203 (see FIG. 303) tobehave differently. For example, in scenarios where the intermittentinfusion is a secondary infusion, the pump 3201, 3202, 3203 may beconfigured to communicate with its companion pumps 3201, 3202, 3203 andautomatically switch back to the primary infusion after issuing anotification that the secondary intermittent infusion has beencompleted. In alternate configurations, the pump may be configured issuea “VTBI ZERO ALERT” and drop the infusion rate to a KVO rate aftercompleting the intermittent infusion. In such configurations, the usermay be required to manually clear the alert before a primary infusion isresumed.

A bolus may also be delivered as a primary intermittent infusion when itmay be necessary or desirable to achieve a higher blood plasma drugconcentration or manifest a more immediate therapeutic effect. In suchcases, the bolus may be delivered by the pump 3201, 3202, 3203 (see FIG.303) executing the primary infusion. The bolus may be delivered from thesame container which the primary infusion is being delivery from. Abolus may be performed at any point during an infusion providing thereis enough infusate to deliver the bolus. Any volume delivered via abolus to a patient is included in the value displayed by the VTBIparameter input field 3314 of the primary infusion.

Depending on the infusate, a user may be forbidden from performing abolus. The dosage of a bolus may be pre-set depending on the specificinfusate being used. Additionally, the period of time over which thebolus occurs may be pre-defined depending on the infusate being used. Insome embodiments, a user may be capable of adjusting these pre-sets byadjusting various setting on the GUI 3300. In some situations, such asthose where the drug being infused has a long half-life (vancomycin,teicoplanin, etc.), a bolus may be given as a loading dose to morequickly reach a therapeutically effective blood plasma drugconcentration.

FIG. 320 shows another rate over time graph in which the flow rate ofthe infusate has been titrated to “ramp” the patient up on the infusate.Titration is often used with drugs which register a fast therapeuticeffect, but have a short half life (such as norepinephrine). Whentitrating, the user may adjust the delivery rate of the infusate untilthe desired therapeutic effect is manifested. Every adjustment may bechecked against a series of limits defined for the specific infusatebeing administered to the patient. If an infusion is changed by morethan a predefined percentage, an alert may be issued. In the exemplarygraph shown in FIG. 320, the rate has been up-titrated once. Ifnecessary, the rate may be up-titrated more than one time. Additionally,in cases where titration is being used to “wean” a patient off of adrug, the rate may be down-titrated any suitable number of times.

FIG. 321 is another rate over time graph in which the infusion has beenconfigured as a multi-step infusion. A multi-step infusion may beprogrammed in a number of different steps. Each step may be defined by aVTBI, time, and a dose rate. Multi-step infusions may be useful forcertain types of infusates such as those used for parenteral nutritionapplications. In the example graph shown in FIG. 321, the infusion hasbeen configured as a five step infusion. The first step infuses a “VTBI1” for a length of time, “Time 1”, at a constant rate, “Rate 1”. Whenthe time interval for the first step has elapsed, the pump moves on tothe second step of the multi-step infusion. The second step infuses a“VTBI 2” for a length of time, “Time 2”, at a constant rate, “Rate 2”.As shown, “Rate 2” is higher than “Rate 1”. When the time interval forthe second step has elapsed, the pump moves on to the third step of themulti-step infusion. The third step infuses a “VTBI 3” for a length oftime, “Time 3”, at a constant rate, “Rate 3”. As shown “Rate 3” is thehighest rate of any steps in the multi-step infusion. “Time 3” is alsothe longest duration of any step of the multi-step infusion. When thetime interval for the third step has elapsed, the pump move on to thefourth step of the multi-step infusion. The fourth step infuses a “VTBI4” for a length of time, “Time 4”, at a constant rate, “Rate 4”. Asshown, “Rate 4” has been down-titrated from “Rate 3”. “Rate 4” isapproximately the same as “Rate 2”. When the time interval for thefourth step of the multi-step infusion has elapsed, the pump move on tothe fifth step. The fifth step infuses a “VTBI 5” for a length of time,“Time 5”, at a constant rate, “Rate 5”. As shown, “Rate 5” has beendown-titrated from “Rate 4” and is approximately the same as “Rate 1”.

The “INFUSION NEAR END ALERT” is triggered during the fourth step of theexample infusion shown in FIG. 321. At the end of the fifth and finalstep of the multi-step infusion, the “VTBI ZERO ALERT” is triggered. Inthe example configuration shown in the graph in FIG. 321, the rate isdropped to a KVO rate after the multi-step infusion has been concludedand the “VTBI ZERO ALERT” has been issued. Other configurations maydiffer.

Each rate change in a multi-step infusion may be handled in a variety ofdifferent ways. In some configurations, the pump 3201, 3202, 3203 (seeFIG. 303) may display a notification and automatically adjust the rateto move on to the next step. In other configurations, the pump 3201,3202, 3203 may issue an alert before changing the rate and wait forconfirmation from the user before adjusting the rate and moving on tothe next step. In such configurations, the pump 3201, 3202, 3203 maystop the infusion or drop to a KVO rate until user confirmation has beenreceived.

In some embodiments, the user may be capable of pre-programminginfusions. The user may pre-program an infusion to automatically beingafter a fixed interval of time has elapsed (e.g. 2 hours). The infusionmay also be programmed to automatically being at a specific time of day(e.g. 12:30 pm). In some embodiments, the user may be capable ofprogramming the pump 3201, 3202, 3203 (see FIG. 303) to alert the userwith a callback function when it is time to being the pre-programmedinfusion. The user may need to confirm the start of the pre-programmedinfusion. The callback function may be a series of audible beeps,flashing lights, or the like.

In arrangements where there are more than one pump 3201, 3202, 3203 (seeFIG. 303), the user may be able to program a relay infusion. The relayinfusion may be programmed such that after a first pump 3201, 3202, 3203has completed its infusion, a second pump 3201, 3202, 3203 mayautomatically being a second infusion and so on. The user may alsoprogram a relay infusion such that the user is alerted via the callbackfunction before the relay occurs. In such a programmed arrangement, therelay infusion may not being until confirmation from a user has beenreceived. A pump 3201, 3202, 3203 may continue at a KVO rate until userconfirmation has been received.

FIG. 322 shows an example block diagram of a “Drug AdministrationLibrary”. In the upper right hand corner there is a box which issubstantially rectangular, though its edges are rounded. The box isassociated with the name “General Settings”. The “General Settings” mayinclude settings which would be common to all devices in a facility suchas, site name (e.g. XZY Hospital), language, common passwords, and thelike.

In FIG. 322, the “Drug Administration Library” has two boxes which areassociated with the names “Group Settings (ICU)” and “Group Settings”.These boxes form the headings for their own columns. These boxes may beused to define a group within a facility (e.g. pediatric intensive careunit, emergency room, sub-acute care, etc.) in which the device isstationed. Groups may also be areas outside a parent facility, forexample, a patient's home or an inter-hospital transport such as anambulance. Each group may be used to set specific settings for variousgroups within a facility (weight, titration limits, etc.). These groupsmay alternatively be defined in other manners. For example, the groupsmay be defined by user training level. The group may be defined by aprior designated individual or any of a number of prior designatedindividuals and changed if the associated patient or device is movedfrom one specific group within a facility to another.

In the example embodiment, the left column is “Group Settings (ICU)”which indicates that the peristaltic pump 2990 is stationed in theintensive care unit of the facility. The right column is “GroupSettings” and has not been further defined. In some embodiments, thiscolumn may be used to designate a sub group, for example operatortraining level. As indicated by lines extending to the box off to theleft of the block diagram from the “Group settings (ICU)” and “GroupSettings” columns, the settings for these groups may include a presetnumber of default settings.

The group settings may include limits on patient weight, limits onpatient BSA, air alarm sensitivity, occlusion sensitivity, default KVOrates, VTBI limits, etc. The group settings may also include parameterssuch as whether or not a review of a programmed infusion is necessaryfor high risk infusates, whether the user must identify themselvesbefore initiating an infusion, whether the user must enter a textcomment after a limit has been overridden, etc. A user may also definethe defaults for various attributes like screen brightness, or speakervolume. In some embodiments, a user may be capable of programming thescreen to automatically adjust screen brightness in relation to one ormore conditions such as but not limited to time of day.

As also shown to the left of the block diagram in FIG. 322, eachfacility may have a “Master Medication List” defining all of theinfusates which may be used in the facility. The “Master MedicationList” may comprise a number of medications which a qualified individualmay update or maintain. In the example embodiment, the “MasterMedication List” only has three medications: Heparin, 0.9% NormalSaline, and Alteplase. Each group within a facility may have its ownlist of medications used in the group. In the example embodiment, the“Group Medication List (ICU)” only includes a single medication,Heparin.

As shown, each medication may be associated with one or a number ofclinical uses. In FIG. 322 the “Clinical Use Records” are defined foreach medication in a group medication list and appear as an expandedsub-heading for each infusate. The clinical uses may be used to tailorlimits and pre-defined settings for each clinical use of the infusate.For Heparin, weight based dosing and non-weight based dosing are shownin FIG. 322 as possible clinical uses. In some embodiments, there may bea “Clinical Use Record” setting requiring the user to review or re-entera patient's weight (or BSA) before beginning an infusion.

Clinical uses may also be defined for the different medical uses of eachinfusate (e.g. stroke, heart attack, etc.) instead of or in addition tothe infusate's dose mode. The clinical use may also be used to definewhether the infusate is given as a primary continuous infusion, primaryintermittent infusion, secondary infusion, etc. They may also be use toprovide appropriate limits on the dose, rate, VTBI, time duration, etc.Clinical uses may also provide titration change limits, the availabilityof boluses, the availability of loading doses, and many other infusionspecific parameters. In some embodiments, it may be necessary to provideat least one clinical use for each infusate in the group medicationlist.

Each clinical use may additionally comprise another expanded sub-headingin which the concentration may also be defined. In some cases, there maybe more than one possible concentration of an infusate. In the exampleembodiment in FIG. 322, the weight base dosing clinical use has a 400mg/250 mL concentration and an 800 mg/250 mL concentration. Thenon-weight based dosing clinical use only has one concentration, 400mg/mL. The concentrations may also be used to define an acceptable rangefor instances where the user may customize the concentration of theinfusate. The concentration setting may include information on the drugconcentration (as shown), the diluents volume, or other relatedinformation.

In some embodiments, the user may navigate to the “Drug AdministrationLibrary” to populate some of the parameter input fields shown in FIGS.312-316. The user may also navigate to the “Drug Administration Library”to choose from the clinical uses for each infusate what type of infusionthe peristaltic pump 2990 will administer. For example, if a user wereto select weight based Heparin dosing on FIG. 322, the GUI 3300 mightdisplay the infusion programming screen shown on FIG. 315 with “Heparin”populated into the medication parameter input field 3302. Selecting aclinical use of a drug may also prompt a user to select a drugconcentration. This concentration may then be used to populate theconcentration parameter input field 3308 (see FIGS. 312-316). In someembodiments, the “Drug Administration Library” may be updated andmaintained external to the peristaltic pump 2990 and communicated to theperistaltic pump 2990 via any suitable means. In such embodiments, the“Drug Administration Library” may not be changeable on the peristalticpump 2990 but may only place limits and/or constraints on programmingoptions for a user populating the parameter input fields shown in FIG.312-316.

As mentioned above, by choosing a medication and clinical use from thegroup medication list, a user may also be setting limits on otherparameter input fields for infusion programming screens. For example, bydefining a medication in the “Drug Administration Library” a user mayalso be defining limits for the dose parameter input field 3310, doserate parameter input field 3318, rate parameter input field 3312, VTBIparameter input field 3314, time parameter input field 3316, etc. Theselimits may be pre-defined for each clinical use of an infusate prior tothe programming of an infusion by a user. In some embodiments, limitsmay have both a soft limit and a hard limit with the hard limit beingthe ceiling for the soft limit. In some embodiments, the group settingsmay include limits for all of the medications available to the group. Insuch cases, clinical use limits may be defined to further tailor thegroup limits for each clinical usage of a particular medication.

Exemplary Battery and Speaker Test

FIG. 323 shows a circuit diagram 13420 having a speaker 3615 and abattery 3420 in accordance with an embodiment of the present disclosure.The battery 3420 may be a backup battery 3450 (FIG. 325A) and/or thespeaker 3615 may be a backup alarm speaker 3468 (FIG. 325B). That is,the circuit 13420 may be a backup alarm circuit, for example, a backupalarm circuit in a medical device, such as a peristaltic pump 2900.

In some embodiments of the present disclosure, the battery 3420 may betested simultaneously with the speaker 3615. When a switch 13422 is inan open position, a voltmeter 13425 may be used to measure the opencircuit voltage of the battery 3420. Thereafter, the switch 13422 may beclosed and the closed-circuit voltage from the battery 3420 may bemeasured. The internal resistance of the battery 3420 may be estimatedby using the known impedance, Z, of the speaker 3615. A processor may beused to estimate the internal resistance of the battery 3420 (e.g., aprocessor of a peristaltic pump 2900). The processor may correlate theinternal resistance of the battery 3420 to the battery's 3420 health. Insome embodiments of the present disclosure, if the closed-circuitvoltage of the battery 3420 is not within a predetermined range (therange may be a function of the open-circuit voltage of the battery3420), the speaker 3615 may be determined to have failed.

In some additional embodiments of the present disclosure, the switch13422 may be modulated such that the speaker 3615 is testedsimultaneously with the battery 3420. A microphone 3617 may be used todetermine if the speaker 3615 is audibly broadcasting a signal withinpredetermined operating parameters (e.g., volume, frequency, spectralcompositions, etc.) and/or the internal impedance of the battery 3420may be estimated to determine if it is within predetermined operatingparameters (e.g., the complex impedance, for example). The microphone3617 (FIG. 325C) may be coupled to the processor. Additionally oralternatively, a test signal may be applied to the speaker 3615 (e.g.,by modulating the switch 13422) and the speaker's 3615 current waveformmay be monitored by an current sensor 13426 to determine the totalharmonic distortion of the speaker 3615 and/or the magnitude of thecurrent; a processor may be monitored these values using the currentsensor 13426 to determine if a fault condition exists within the speaker3615 (e.g., the total harmonic distortion or the magnitude of thecurrent are not within predetermined ranges).

Various sine waves, periodic waveforms, and/or signals maybe applied tothe speaker 3615 to measure its impedance and/or to measure theimpedance of the battery 3420. For example, a processor of a peristalticpump 2900 disclosed herein may modulate the switch 13422 and measure thevoltage across the battery 3420 to determine if the battery 3420 and thespeaker 3615 has an impedance within predetermined ranges; if theestimated impedance of the battery 3420 is outside a first range, theprocessor may determine that the battery 3420 is in a fault condition,and/or if the estimated impedance of the speaker 3615 is outside asecond range, the processor may determine that the speaker 3615 is in afault condition. Additionally or alternatively, if the processor cannotdetermine if the battery 3420 or the speaker 3615 has a fault condition,but has determined that at least one exists in a fault condition, theprocessor may issue an alert or alarm that the circuit 13420 is in afault condition. The processor may alarm or alert a user or a remoteserver of the fault condition. In some embodiments of the presentdisclosure, the peristaltic pump 2990 will not operate until the faultis addressed, mitigated and/or corrected.

Electrical System

The electrical system 4000 of the peristaltic pump 2990 is described ina block schematic in FIGS. 324, 325A-325G. The electrical system 4000controls the operation of the peristaltic pump 2990 based on inputs fromthe user interface 3700 and sensors 3501. The electrical system 4000 maybe a power system comprised of a rechargeable main battery 3420 andbattery charging 3422 that plugs into the AC mains. The electricalsystem 4000 may be architected to provide safe operation with redundantsafety checks, and allow the peristaltic pump 2990 to operate in failoperative modes for some errors and fail safe for the rest.

The high level architecture of multiple processors is shown in FIG. 324.In one example, the electrical system 4000 is comprised of two mainprocessors, a real time processor 3500 and a User Interface and SafetyProcessor 3600. The electrical system may also comprise a watch-dogcircuit 3460, motor control elements 3431, sensors 3501 and input/outputelements. One main processor, referred to as the Real Time Processor(RTP) 3500 may controls the speed and position of the motor 3072 thatactuates the plunger 3091, and valves 3101,3111. The RTP 3500 controlsthe motor 3072 based on input from the sensors 3501 and commands fromthe User Interface & Safety processor (UIP) 3600. The UIP 3600 maymanage telecommunications, manage the user interface 3701, and providesafety checks on the RTP 3500. The UIP 3600 estimates the volume pumpedbased on the output of a motor encoder 3438 and may signal an alarm oralert when the estimated volume differs by more than a specified amountfrom a desired volume or the volume reported by the RTP 3500. The watchdog circuit 3460 monitors the functioning of the RTP 3500. If the RTP3500 fails to clear the watch dog 3460 on schedule, the watch dog 3460may disable the motor controller, sound an alarm and turn on failurelights at the user interface 3701. The sensor 3130 may measure therotational position of the cam shaft 3080 and the plunger 3901. The RTP3500 may use the sensor inputs to control the motor 3072 position andspeed in a closed-loop controller as described below. Thetelecommunications may include a WIFI driver and antenna to communicatewith a central computer or accessories, a bluetooth driver and antennato communicate with accessories, tablets, cell-phones etc. and a NearField Communication (NFC) driver and antenna for RFID tasks and abluetooth. In FIG. 324 these components are collectively referred towith the reference number 3721. The user interface 3701 may include adisplay, a touch screen and one or more buttons to communicate with theuser.

The detailed electrical connections and components of the electricalsystem 4000 are shown in FIG. 325A-325G. The sensors 3130, 3530, 3525,3520 and part of the RTP 3500 are shown in FIG. 325A. The sensorsmonitoring the peristaltic pump 2990 that are connected to the RTP 3500may comprise the rotary position sensor 3130 monitoring the cam shaftposition and two linear encoders 3520, 3525 that measure the position ofthe plunger 3091 as shown. One linear encoder 3520 measures the positionof the magnet (3096A in FIG. 268) upstream side of the plunger 3091. Theother linear encoder 3525 measures the position of the magnet (3096A inFIG. 268) on the downstream side of the plunger 3091. In anotherembodiment, the position of the plunger may be measured with a singlemagnet and linear encoder. Alternatively, RTP 3500 may use output ofonly one linear encoder if the other fails. A thermistor 3540 provides asignal to the RTP 3500 indicative of the infusion line 3210 temperature.Alternatively the thermistor 3540 may measure a temperature in theperistaltic pump 2990.

As shown, the electrical system 4000 defines specific part numbers forvarious components. For example, the thermistor 3540 is defined as a “2XSEMITEC 103JT-050 ADMIN Set THERMISTOR” These part numbers should not beconstrued as limiting in any way whatsoever. In different embodiments,suitable replacement components may be used in place of the specificparts listed in the FIGS. 325A-325G. For example the thermistor 3540 maynot be a “2X SEMITEC 103JT-050 ADMIN Set THERMISTOR”, but rather anysuitable replacement thermistor 3540. In some embodiments, theelectrical system 4000 may comprise additional components. In someembodiments the electrical system 4000 may comprises fewer componentsthan the number of components shown in FIGS. 325A-325G

The two infusion line sensors located downstream of the peristaltic pump2990, an air-in-line sensor 3545 and an occlusion sensor 3535 may beconnected to the RTP 3500. An air-in-line sensor 3545 detects thepresence of air in the section of infusion line 3210 near theair-in-line sensor 3545. In one example, the air-in-line sensor 3545 maycomprise an ultra-sonic sensor 3545B, a logic unit 3545A and a signalconditioning unit 3545C.

The occlusion sensor 3535 measures the internal pressure of fluid in theinfusion line 3535. In an example embodiment, the occlusion sensor 3535may comprise a force sensor 3535B, a current excitation IC 3535A, asignal amplifier 3535C and a data buffer 3535D. The data buffer chip3535D may protect the RTP 3500 from over-voltages due to high forcesform pressures applied to the force sensor 3535B.

The watchdog circuit 3460 is shown in FIGS. 325A-325C. The watch dogcircuit is enabled by an I2C command from the RTP 3500. The watch dogcircuit 3460 may signal an error and disable the motor control 3430 ifit does not receive a signal from the RTP 3500 at a specified frequency.The watch dog circuit 3460 may signal the user via an audible alarm. Theaudible alarm may be issued via an amplifier 3464 and/or backup speaker3468. The watch dog circuit 3460 may signal the user with visual alarmLEDs 3750 (shown in FIG. 325D). In one embodiment, the RTP 3500 must“clear” the watch dog circuit 3460 between 10 ms and 200 ms after thewatch dog circuit's last clear. In one embodiment, the watch dog circuit3460 is comprised of a window watchdog 3450A, a logic circuit 3460Bincluding one or more flip-flop switches and an IO expander 3460C thatcommunicates with the RTP 3500 over an I2C bus. A backup battery 3450provides power to the watchdog circuit 3460 and backup speaker system(which may comprise an audio amplifier 3464, and a backup speaker 3468)in case the main battery 3420 fails. The backup battery 3450 providespower to the RTP 3500 and UIP 3600 to maintain the internal timekeeping,which may be especially desirable when the main battery 3420 is changed.The RTP 3500 may also monitor the voltage of the backup battery 3450with a switch such as the “FAIRCHILD FPF1005 LOAD SWITCH” 3452 shown inFIG. 325A.

The RTP 3500 directly controls the speed and position of the motor 3072which controls the position and speed of the plunger and valves. Themotor 3072 may be any of a number of types of motors including a brushedDC motor, a stepper motor or a brushless DC motor. In the embodimentillustrated in FIGS. 325-325G, the peristaltic pump 2990 is driven by abrushless direct current (BLDC) servo motor 3072 where the rotaryposition sensor 3130 measures the position of the cam-shaft. In oneexample embodiment, the RTP 3500 receives the signals from thehall-sensors 3436 of a brushless DC motor 3072 and does the calculationsto commutate power to the windings of the motor 3072 to achieve adesired speed or position. The commutation signals are sent to the motordriver 3430 which selectively connects the windings to the motor powersupply 3434. The motor 3072 is monitored for damaging or dangerousoperation via current sensors 3432 and a temperature sensor 3072 a.

The signals from the hall sensors 3436 may be supplied to both the RTP3500 and to an encoder 3438. In one embodiment, three hall sensorsignals are generated. Any two of the three hall signals are sent to theencoder 3438. The encoder 3438 may use these signals to provide aposition signal to the UIP 3600. The UIP 3600 estimates the total volumeof fluid dispensed by the peristaltic pump 2990 by interpreting theposition signal of the encoder 3438. The UIP 3600 estimates the totalvolume by multiplying the number of complete cam-shaft revolutions timesa given stroke volume. The total volume estimate of the UIP 3600 assumeseach plunger stroke supplies the given amount of fluid. The amount offluid supplied per stroke is determined empirically during developmentand stored in memory. Alternatively, each peristaltic pump 2990 may becalibrated during assembly to establish the nominal volume/stroke thatmay be stored in memory. The UIP 3600 estimated volume may then becompared at regular intervals to the expected volume from the commandedtherapy. In some embodiments, the interval between comparisons may beshorter for specific infusates, for example short-half life infusates.The therapy may specify, among other parameters, a flow rate, aduration, or a total volume to be infused (VTBI). In any case, theexpected volume for a programmed therapy at a given time during thattherapy may be calculated and compared to the volume estimated by theUIP 3600. The UIP 3600 may signal an alert if the difference between UIP3600 estimated volume and the therapy expected volume is outside apredefined threshold. The UIP 3600 may signal an alarm if the differencebetween UIP 3600 estimated volume and the therapy expected volume isoutside of another predefined threshold.

The UIP 3600 may also compare the estimated volume to the volumereported by the RTP 3500. The UIP 3600 may signal an alert if thedifference between UIP 3600 estimated volume and the RTP 3500 reportedvolume is outside a predefined threshold. The UIP 3600 may signal analarm if the difference between UIP 3600 estimated volume and the RTP3500 reported volume is outside a second threshold.

In some embodiments, the UIP 3600 may compare the RTP 3500 reportedvolume to therapy expected volume and signal an alert if the two valuesdiffer by more than a predefined threshold. The UIP 3600 may signal analarm if the difference between the RTP 3500 reported volume and thetherapy expected volume differ by more than a predefined threshold. Thevalues of the alert and alarm thresholds may be different forcomparisons between different sets of volumes including the UIP 3600estimated volume, the RTP 3500 calculated volume and the therapyexpected volume. The thresholds may be stored memory. The thresholds mayvary depending on a number of other parameters, such as but not limitedto, medication, medication concentration, therapy type, clinical usage,patient or location. The thresholds may be included in the DERS databaseand downloaded from the device gateway server.

The slide clamp or slide occluder sensor 3152 and the door sensor 3162communicate with both the RTP 3500 and the UIP 3600 as shown in FIGS.325B, 325F. In one embodiment the sensors are magnetic null sensors thatchange state when for example the slide occluder 3200 is detected or thedoor latch hook 3025C engages the pump body. The RTP 3500 or the UIP3600 may enable the motor power supply 3434 only while the processorsreceive signals indicating that the slide occluder 3200 is in place andthe door assembly 3021 is properly closed.

An RFID tag 3670 (FIG. 325C) may be connected by an I2C bus to the UIP3600 and to a near field antenna 3955. The RFID tag 3670 may be used bymed-techs or other users or personnel to acquire or store informationwhen the peristaltic pump 2990 is in an unpowered state. The UIP 3600may store service logs or error codes in the RFID tag 3670 that can beaccessed by an RFID reader. A med-tech, for example, could inspectunpowered peristaltic pumps 2990 in storage or evaluate non-functioningperistaltic pumps 2990 by using an RFID reader to interrogate the RFIDtag 3670. In another example, a med-tech may perform service on theperistaltic pump 2990 and store the related service information in theRFID tag 3670. The UIP 3600 may then pull the latest service informationfrom the RFID tag 3670 and store it in memory 3605.

The main battery 3420 may supply all the power to the peristaltic pump2990. The main battery 3420 is connected via a system power gatingelement 3424 to the motor power supply 3434. All of the sensors andprocessors may be powered by one of the several voltage regulators 3428.The main battery 3420 is charged from AC power via a battery charger3422 and an AC/DC converter 3426. The UIP 3600 may be connected to oneor more memory chips 3605.

The UIP 3600 controls the main audio system which comprise a mainspeaker 3615 and the audio-chips 3610, 3612. The main audio system maybe capable of producing a range of sounds indicating, for example,alerts and alarms. The audio system may also provide confirmatory soundsto facilitate and improve user interaction with the touch screen 3755and display 3725. The main audio system may include a microphone 3617that may be used to confirm the operation of the main speaker 3615 aswell as the backup speaker 3468. The main audio system may produce oneor more tones, modulation sequences and/or patterns of sound and theaudio codec chip 3610 may compare the signal received from themicrophone 3617 to the signal sent to the main speaker 3615. The use ofone or more tones and comparison of signals may allow the system toconfirm main speaker 3615 function independently of ambient noise.Alternatively the UIP 3600 or the audio codec 3610 may confirm that themicrophone 3617 produced a signal at the same time a signal was sent tothe speaker amplifier 3612.

The UIP 3600 may provide a range of different wireless signals fordifferent uses. The UIP 3600 may communicate with the hospital wirelessnetwork via a dual band wifi using chips 3621, 3620 and 3622 andantennas 3720, 3722. The spatially diverse dual antenna may be desirablebecause it may be capable of overcoming dead spots within a room due tomultiple paths and cancellation. A hospital device gateway maycommunicate DERS (Drug Error Reduction System), CQI (Continuous QualityImporvement), prescriptions, etc. to the peristaltic pump 2990 via thewifi system.

The bluetooth system, using the same chips 3621, 3620 and 3622 andantennas 3720, 3722, provides a convenient method to connect auxiliariesto the peristaltic pump 2990 that may include pulse-oximeters, bloodpressure readers, bar-code readers, tablets, phones, etc. The bluetoothmay include version 4.0 to allow low power auxiliaries which maycommunicate with the peristaltic pump 2990 periodically such as, forexample, a continuous glucose meter that sends an update once a minute.

The NFC system is comprised of an NFC controller 3624 and an antenna3724. The controller 3624 may also be referred to as an RFID reader. TheNFC system may be used to read RFID chips identifying drugs or otherinventory information. The RFID tags may also be used to identifypatients and caregivers. The NFC controller 3624 may also interact witha similar RFID reader on, for example, a phone or tablet computer toinput information including prescriptions, bar-code information,patient, care-giver identities, etc. The NFC controller 3624 may alsoprovide information to the phone or tablet computers such as theperistaltic pump 2990 history or service conditions. The RFID antennas3720 and 3722 or NFC antenna 3724 may preferably be located around ornear the display screen, so all interaction with the pump occurs on ornear the screen face whether reading an RFID tag or interacting with thedisplay touch screen 3725, 3735.

The UIP 3600 may include a medical grade connector 3665 so that othermedical devices may plug into the peristaltic pump 2990 and provideadditional capabilities. The connector 3665 may implement a USBinterface.

The display 3700 includes the antennas 3720, 3722, 3725, the touchscreen 3735, LED indicator lights 3747 and three buttons 3760, 3765,3767. The display 3700 may include a backlight 3727 and an ambient lightsensor 3740 to allow the screen brightness to automatically respond toambient light. The first button 3760 may be the “Power” button, whileanother button 3765 may be an infusion stop button. These buttons 3760,3765, 3767 may not provide direct control of the peristaltic pump 2990,but rather provide a signal to the UIP 3600 to either initiate orterminate infusion. The third button 3767 will silence the alarm at themain speaker and at the secondary speaker. Silencing the alarm will notclear the fault, but will end the audible alarm. The electric system4000 described above, or an alternative embodiment of the electricalsystem 4000 described above, may be used with any of peristaltic pumpswith linear position sensors.

Controls

The pumping algorithms provide substantially uniform flow by varying therotation speed of the motor 3072 over a complete revolution. At lowflows, the motor 3072 turns at a relatively high rate of speed duringportions of the revolution when the plunger 3091 is not moving fluidtoward the patient. At higher flow rates, the motor 3072 turns at anearly constant speed throughout the revolution to minimize powerconsumption. At the high flow rates, the motor 3072 rotation rate isproportional to the desired the flow rate. The pump algorithm use linearencoders 3520, 3525 (FIG. 325A) above the plunger 3091 to measure volumeof fluid pumped toward the patient. The pump algorithm use linearencoders 3520, 3525 (FIG. 325A) above the plunger 3091, the rotationencoder 3130 (FIG. 325A) near the cam-shaft 3080 and the air-in-linesensor 3545 downstream of the plunger 3091 to detect one or more of thefollowing conditions: downstream occlusions, upstream occlusions/emptybag, leaks and the amount of air directed toward the patient.

One embodiment of the valve 3101, 3111 openings and plunger 3091position is plotted in FIG. 326. Three time periods are identified inFIG. 326 including a refill 826, pressurization 835 and deliver 840period. In addition, period “A” occurs between the pressurization period835 and Delivery period 840, and period “B” occurs between the Deliveryperiod 840 and Refill period 830. The inlet valve position 820, outletvalve position 825 and plunger position 815 are plotted on a sensorsignal over cam angle graph over a complete cam shaft 3080 rotation.

The refill period 830 occurs while the inlet valve 820 is held off theinfusion line 3210 and the plunger 3091 is lifted off the infusion line3210 by the plunger cam 3083. The refill period 830 ends and thepressurization period 835 begins as the inlet valve 3101 is closing. Theplunger cam 3083 is full retracted during the pressurization period 835to allow the plunger 3091 to land on the filled infusion line 3210. Thepressurization period 835 ends several cam angle degrees past the pointwhere the plunger cam 3083 reaches its minimum value. After a waitingperiod “A”, the plunger cam 3083 lifts until it reaches the height wherethe plunger 3091 is expected to be. The delivery period 840 begins whenthe outlet valve 3111 starts to open and lasts until the outlet valve3111 closes again. The plunger cam 3083 rotates causing the plunger 3091to descend during the delivery period 840 pushing fluid toward thepatient.

The RTP 3500 may determine the volume of fluid delivered toward thepatient for each stroke based on signals from the rotary encoder 3130measuring the angle of the camshaft 3080 and from the linear encoder3525, 3520 measurements plunger 3091 position. The volume of each strokemay be measured by subtracting the height of the plunger 3091 at the endof the delivery period 840 from the height of the plunger 3091 at theend of pressurization period 835. The height of the plunger 3091 may bedetermined from signals of one or both of the linear encoders 3020,3025, where the height approximates the distance of the plunger tip3091B from the platen 3022. The end of the delivery period 840 and theend of the pressurization period 835 may be determined from the rotaryencoder 3130 measuring the angle of the crank shaft. The measured heightdifference 845 may be empirically associated with pumped volumes and theresult stored in a lookup table or in memory in the controller. Thevolume vs. stroke table may be determined during development and beprogrammed into each peristaltic pump 2990 during manufacture.Alternatively, the measured change in plunger 3091 height may becalibrated to pumped volume for each peristaltic pump 2990 or pumpingmechanism 3000 during the manufacturing process.

In one embodiment, the pumped volume is calibrated plunger 3091positions as:

V _(i) =A+B*(h _(P) −h _(D))

where V_(i) is the pumped volume, A and B are fitting coefficients,h_(P) is the plunger 3091 position at the end of the pressurizationperiod 835 and h_(D) is the plunger 3091 position at the end of thedelivery period 840.

The speed of the motor 3072 varies with the flow rate and it varies overa single revolution for lower flow rates. In one example, the motor 3072rotation is relatively constant for commanded flow rates aboveapproximately 750 ml/hr. The motor 3072 speed is controlled torelatively slower speeds during intake and deliver flow rates forcommanded flow rates below approximately 750 ml/hr.

The motor 3072 moves at a constant speed during the pressurizationperiod 835 for all pumping rates. In one example the motor 3072 turns atthe speed required to deliver fluid at the highest flow rate. In oneexample the motor 3072 turns at 800°/second during the pressurizationperiod 835, which corresponds to the peristaltic pump 2990 to delivering1200 mL/Hr. Running the motor 3072 at a fixed high speed during thepressurization period 835 may advantageously minimize no-flow periodswhich improve uniformity of fluid flow. Running the motor 3072 at afixed high speed during the pressurization period 835 may advantageouslycreate a consistent measurement of the filled infusion line 3210 heightby compressing the plastic walls of the infusion line 3210 at the samerate each time. Not being limited to a single theory, one theory holdsthat the plastic infusion line 3210 continues to yield after beingcompressed, which would produce a lower height for the filled infusionline 3210 the longer the time between compression and measurement. Theplastic may exhibit visco-elastic properties so that the amount ofstrain in the plastic changes with the rate of compression, which inturn would change the measured height of the plastic infusion line 3210.

Low Flow Mode

The pumping algorithm to produce a desired flow rate may control motor3072 speed differently during the refill and delivery periods 830,840for relatively lower flow rates as compared to higher flow.

In the low flow mode the motor 3072 is controlled during the deliveryperiod 840 to control the cam-shaft 3080 position in order to produce apredefined volume trajectory. The volume trajectory is the volume offluid delivered to the patient verses time. The predefined volumetrajectory usually occurs over many cam-shaft 3080 rotations, so thatthe delivery period 840 must deliver a full revolution's worth of fluidat the trajectory speed in the shorter delivery period 840.

The motor 3072 speed during the refill period 830 is adjusted to producea full infusion line 3210 as measured at the plunger 3091 position atthe end of the pressurization period 835. The controller will slow themotor 3072 speed if the infusion line 3210 is not full in the previouspump cycle. The refill period 830 is selected such that the plunger 3091lifts off of the hard stop 3022A (FIG. 277) slowly (at lower flow rates)in order to minimize cavitation and air bubble generation.

At all other times the motor 3072 spins at the Delivery Stroke Velocity.In short, this is the velocity at which the cam shaft 3080 must completea revolution in order to keep up with the trajectory volume, limited tovalues greater than 500° per second.

High Flow Mode

In high flow mode, the refill and delivery periods 830, 840 occur at theDelivery Stroke Velocity. The pressurization period 835 continues tooccur at 800° per second. The Delivery Stroke Speed is continuouslyupdated based on the previous volume measurement.

Delivery Stroke Velocity

The Delivery Stroke Velocity is the velocity at which the cam shaft 3080needs to rotate in order for the controller to maintain the requestedflow rate. This value is limited to speeds greater than 500° per second(approx. 700 mL per Hr). This value is also limited to less than thevelocity required to maintain the requested flow rate in the case wherethe peristaltic pump 2990 is only delivering 80 uLs per stroke. Thiswould be a significant under-fill and likely the result of some issueupstream of the peristaltic pump 2990. The velocity is calculated usingthe current volume delivered, requested volume delivered, previousstroke volume, and requested flow rate as pictured in FIG. 327.

A = Trajectory  Volume, at  end  of  previous  strokeB = Measured  Delivered  Volume, as  of  previous  strokeD = Expected  Stroke  Volume C = B + D − AT = Requested  Trajectory  Flow  Rate C = T(t)$t = {\frac{C}{T} = \frac{B + D - A}{T}}$${\overset{.}{\theta} = {{Cam}\mspace{14mu} {Shaft}\mspace{14mu} {Velocity}}},\frac{\deg}{\sec}$$\overset{.}{\theta} = {\frac{360^{{^\circ}}}{t} = \frac{360^{{^\circ}}*T}{B + D - A}}$

In order to achieve a consistent flow rate, particularly during low flowrate deliveries, the rate at which the plunger 3091 descends must becontrolled. The goal is to keep the flow as continuous and as close tothe trajectory volume as possible. This is complicated by periods wherethe peristaltic pump 2990 does not deliver (refill, pressurize, etc).

To achieve continuous flow, at the start of the delivery stroke thevolume delivered as part of the previous stroke should be equal thetrajectory volume. This ensures a smooth initial delivery (avoiding aninitial “rush” to catch up). In order to accomplish this, by the end ofthe previous stroke the peristaltic pump 2990 must have over-deliveredby the volume that is accrued during the Refill and Pressurization 830,835 phases. This Over-Delivery volume is applied throughout the deliverystroke, such that at the start none of it is applied, but by the end thefull volume is added.

An additional consideration is the fill volume. Shown in FIG. 328 is agraph of the volume delivered versus the cam angle over various fillvolumes for several pump cycles. In the case of a completely fullpumping chamber (approx. 150 uLs), there is a spurt of fluid as theoutlet valve 3111 first opens. Alternatively, in the case of fillvolumes lower than about 130 uLs, there is a tendency to pull fluid.Both of these occurrences negatively affect flow continuity. In totemper this, in some embodiments a target fill volume is set to minimizethese effects.

The graph in FIG. 328 shows multiple delivery strokes, with the volumedelivered normalized to 135 uLs. Most of the stroke is repeatable, onceadjusting for the fill volume. The result of all of this is athird-order function that calculates a desired cam shaft 3080 anglegiven a requested volume. See below for the pertinent equations.

Variables

-   -   n=Current Delivery Stroke    -   i=Current Motor Control ISR cycle    -   f(x)=3rd Order Polynomial Fit    -   E_(n)=Expected Pulse Volume given a Fill Volume per current        delivery stroke    -   P_(n)=Pulse Volume per f(x) per delivery stroke (this is a        constant)    -   S_(n)=Expected Volume Shortage of current stroke    -   T_(i)=Current Target Volume via Trajectory    -   V_(n−1)=Measured Delivered Volume as of completion of previous        delivery stroke    -   Q_(i)=Target Volume to be Delivered at time i    -   F_(i)=Fraction of Stroke completed at time i    -   O_(n)=Overhead Volume (Trajectory volume increase during        nondelivery portions of cycle)    -   θ_(i)=Requested Cam Shaft Angle    -   θ₀=Initial Cam Shaft Angle at start of delivery stroke

EQUATIONS S_(n) = P_(n) − E_(n) Q_(i) = T_(i) − V_(n − 1)$F_{i} = \frac{Q_{i}}{E_{n}}$θ_(i) = f(Q_(i) + S_(n) + O_(n)F_(i)) + θ₀

In some embodiments, the motor 3072 velocity during the delivery strokeis limited to no faster than the Delivery Stroke Velocity. The result ofthis is that at high speeds, the requested position is always ahead ofthe speed-limited position. At lower flow rates, the cam shaft 3080position quickly reaches the calculated position and subsequentlyfollows the above algorithm.

Down-Stream Occlusion Detection

The controller may determine whether a downstream occlusion exists bycomparing the pressures or forces measured at the occlusion detector3535 (3068 in FIG. 257) during the delivery period 840, during theprevious refill period 830 and the filtered pressure data from previouspump cycles. Here a pump cycle is a complete revolution of the cam-shaft3080 producing a refill, pressurization and delivery period (830, 835,840). A downstream occlusion will be determined to exist by theprocessor if any one of several conditions occur. The pressures orforces measured by the sensor 3545B may be low pass filtered to rejectspurious noise. In one embodiment, the low pass filter may reject noiseabove 1000 Hz. A plot of filtered hypothetical pressures over time isplotted in FIG. 329, where the pressure oscillates between lowerpressures 850 when outlet valve 3111 (FIG. 259) is closed and highpressures 851 when the outlet valve 3111 is open and flow is beingforced through the infusion line 3210 that is pressed against thepressure sensor 3535B. A downstream occlusion may create greater flowresistance as fluid is pushed toward the patient resulting in higherpeak pressures and/or higher pressures when the outlet valve 3111 isclosed as the restricted fluid slowly flows past a partial occlusion.

A first example of a downstream occlusion test compares the measuredchange in minimum pressure (P_(MIN)) of the current cycle to a constantvalue. If the change in P_(MIN) is greater than a predefined value, thecontroller will declare an occlusion. The change in P_(MINi) is thedifference in the minimum pressure of the current pump cycle to theminimum pressure of the previous pump cycle P_(MINi−1).

A downstream occlusion will be declared for cycle i, if

P*_(MIN i) exceeds a first given threshold.

In another embodiment, the change in P_(MIN) is calculated as adifference between the current change in P_(MIN) to the filtered changein P_(MIN):

P* _(MIN i) =f*

P _(MIN i)+(1−f)*

P* _(MIN i−1)

FP _(MIN i) =

P _(MIN i) −

P* _(MIN i−1).

where f is the weighting value for the newest data. In one example, theweighting value for f is 0.05. If

FP_(MIN i) is greater than a second given threshold, the controller maydeclare an occlusion for cycle i.

In another embodiment, a downstream occlusion is declared when the sumof the changes in P_(MIN) exceeds a third given threshold, where the sumof the changes in P_(MIN) is calculated as:

IP _(MIN) =

P _(MIN i) −

P _(L).

where

P_(L) is the initial pressure minus the minimum pressure. If IP_(MIN)exceeds a third given value, then the controller may declare anocclusion.

A forth example of a downstream occlusion test compares the maximumpressure to a minimum pressure (P_(MIN)) of the current pump cycle:

P _(P i) =P _(MAX i) −P _(MIN i−1).

where P_(MAX I) is the maximum pressure during the delivery period 840.The controller may declare a downstream occlusion if the

P_(P i) exceeds a forth given threshold.

In the event of a downstream occlusion, the controller may command thepump to backflow fluid through the peristaltic pump 2990 in order torelieve the pressure on the occlusion. It may be beneficial to relievethe pressure on the occlusion to avoid a bolus of fluid to be directedto the patient when the occlusion is relieved. In one example, theocclusion may be cleared by unpinching or unkinking the infusion line3210 between the peristaltic pump 2990 and the patient.

Upstream Occlusion/Air-in-Line Measurement

The controller may detect an upstream occlusion or determine the volumeof air pumped toward the patient based on the measured volume per strokeand historical volume per stroke average. The controller calculates anunder-deliver volume for each stroke V_(UD i) as:

V _(UD i) =V _(avg i) −V _(i)

V _(avg i) =fv*V _(i)+(1−fv)*V _(avg i−1)

where fv is a weighting factor for the volume and V_(i) is the volume offluid pumped during cycle i. The controller maintains a buffer ofseveral V_(UD) values, dropping the oldest one as the newest V_(UD) isadded. If the air-in-line detector 3545 (3066 in FIG. 257) detects abubble, the controller will assume the V_(UD i) represents an airbubble. If the air-in-line detector 3545 does not detect air, then theV_(UD i) is assumed to be under-delivered volume. The controller maydeclare an upstream occlusion, if V_(UD i) is greater than a given valuethe air-in-line detector 3545 does not detect air. The controller maydetermine the volume of air pumped toward the patient and may signal analert if the air volume exceeds a first value over a first time periodand alarm if air volume exceeds a second value over a second timeperiod. In one example, the controller calculates the volume of the airbubble (V_(BUBBLE)) by summing the under-deliver volumes (V_(UD i)) foreach stroke when the air-in-line detector 3545 signals the presence ofair and some number of V_(UD i) before the first detection of air:

V _(BUBBLE) =

V _(UD i).

In one example, V_(BUBBLE) is calculated for each stroke when theair-in-line detector 3545 signals the presence of air and the threeV_(UD i) before the first detection of air.

In an alternative embodiment, the controller calculates a under-delivervolume for each stroke V_(UD i) as:

V _(UD i) =V _(T) −V _(i)

where V_(T) is the nominal volume of one pump cycle that is stored inthe controller. In this alternative embodiment, the controllercalculates the total volume of the air bubble (V_(BUBBLE)) by summingthe under-deliver volumes (V_(UD i)) for each stroke when theair-in-line detector 3545 signals the presence of air and some number ofV_(UD i) before the first detection of air:

V _(BUBBLE)=

(V _(UD I) −V* _(UD i))

.

V* _(UD i) =fv*V* _(UD i)+(1−fv)*V* _(UD i−1)

where .

V_(UD i) is the filtered value of V_(UD) and fv is the weightingaverage. In one example, V_(BUBBLE) is calculated for each stroke whenthe air-in-line detector 3545 signals the presence of air and the threeV_(UD i) before the first detection of air.In one embodiment, each bubble volume V_(BUBBLE) is added to a buffer ofbubble volumes covering a set period of time and the sum of the bubblevolumes in the buffer are evaluated against a standard. If the sum ofthe bubble volumes exceeds a given threshold, then the controller alarmsfor air in line. The controller may reverse the peristaltic pump 2990 topull the air back from the patient. In one example, the buffer capturesthe most recent 15 minutes of operation and the air volume threshold isset to a value between 50 and 1000

l. In one example, bubble volumes smaller than a given value may becounted in the summation of the bubble volume. In one example, bubblevolumes less than 10

l may be ignored. The air volume threshold may be user setable, or maybe part of the DERS data that is downloaded from the device servergateway. The DERS and device server gateway are described in detail inthe cross referenced non-provisional application for SYSTEM, METHOD, ANDAPPARATUS FOR ELECTRONIC PATIENT CARE (ATTORNEY DOCKET NO. J85).

Leak Test

A leak is determined at the end of the pressurization period 835 bymonitoring the plunger 3091 position while the plunger L-shaped camfollower 3090 is not resting on the plunger cam 3083 and the plunger tip3091B is resting on the infusion line 3210. If the plunger 3091 moves bymore than a given value over a given time indicating that fluid hasleaked past the valves 3101, 3111. In one embodiment, the peristalticpump 2990 is stopped for half a second every six seconds at the end ofpressurization period 835 to monitor the plunger 3091 position todetermine if a leak exists between the valves 3101, 3111.

State Diagram for Delivery of Fluid by the Peristaltic Pump

The state diagram for the software that controls the delivery of fluidis pictured in FIG. 330. The Delivery Top State (capitalized phasesherein may refer to variables, processes, or data structures, etc.depending on context) is the SuperState for the entire pump controller3430 and comprises the Idle State and the Running State. The Idle Stateis entered upon starting the pump controller 3430, completing adelivery, or stopping/aborting a delivery. The Running State is theSuperState for all states that involve actuating the motor 3072 orperforming a delivery. The Running State also handles Freeze commands.

The Delivery State is the SuperState for all states involving performinga delivery. This state handles Stop commands, which had two behaviorsdepending on the current state. If commanded during an active deliverythe peristaltic pump 2990 will finish delivery after current stroke iscompleted. If the peristaltic pump 2990 is currently in the freezestate, it will immediately end the delivery.

The Start Deliver State signifies the beginning of a delivery cycle, orone rotation of the cam shaft 3080. The peristaltic pump 2990 willtransition to one of three states depending on the current conditions.If enough time has elapsed since the previous leak check, the Moving toLeak Check Position State is called. If the previous delivery was frozenand aborted mid-stroke, the Moving to Plunger Down State is entered inorder to resume delivering where the previous delivery ended. Otherwise,the motor controller 3430 transitions to the Moving to PressurizedPosition State.

The Moving to Leak Check Position State commands the motor controller3430 to move to and hold position at the Valves Closed Plunger Downposition. The motor 3072 velocity is commanded to move at 800° persecond. Upon receiving notification that the cam shaft 3080 has reachedthe desired position the Pressurized Position measurement is taken forvolume calculations and the Waiting for Leak Check State is called.

The Waiting for Leak Check State idles until a set amount of time haselapsed, allowing the infusion line 3210 to settle and, in the case of aleak, fluid to escape the pumping chamber. Once the time has elapsed,the plunger 3091 position is measured again and compared to thePressurized Position in order to determine the presence of a leakcondition. The Fault Detector is told that the delivery stroke isstarting in order to monitor for air and occlusions and the Moving toPlunger Down Position State is called.

The Moving to Pressurized Position State commands the motor controller3430 to move towards and send a notification upon reaching the ValvesClosed Plunger Down position. It will continue to move upon reachingthis position until a new command is issued. The motor 3072 velocity iscommanded to move at 800° per second.

Upon receiving notification that the cam shaft 3080 has reached thedesired position the Pressurized Position measurement is taken forvolume calculations and the Moving to Plunger Down Position State iscalled. The Fault Detector is told that the delivery stroke is startingin order to monitor for air and occlusions.

The Moving to Plunger Down Position State controls the cam shaft 3080position throughout the portion of the cam shaft 3080 rotation that theoutlet valve 3111 is open. The cam shaft 3080 position is controlled insuch a way as to attempt to keep the flow as consistent as possible.During this state, the motor 3072 velocity is again limited to nogreater than the calculated Delivery Stroke Velocity. There are twopaths by which the motor controller 3430 can exit this state. In thefirst case, the state is notified once the cam shaft 3080 reaches theOutlet Open Plunger Down position. Alternatively, if the total deliveryvolume reaches the commanded volume during the stroke, the cam shaft3080 position is frozen and the state is notified that the stroke iscomplete.

Upon being notified that cam shaft 3080 has reached the Outlet OpenPlunger Down position, the plunger 3091 position is stored as the PostDelivery Position measurement and the Fault Detector is told that thedelivery stroke is complete. Using this measurement, the volumedelivered is calculated (using the calibration in Section 3). If theperistaltic pump 2990 was stopped mid-stroke, the volume delivered isestimated using the current position and the fill volume. Using theupdated delivery volume information, the updated Delivery StrokeVelocity is calculated. Finally, in the case where the delivery volumehas been reached, the peristaltic pump 2990 calls the End Deliver State.Otherwise the Moving to Fill Position State is entered.

The Moving to Fill Position State commands the motor controller 3430 tomove towards and send a notification upon reaching the Inlet Valve OpenPlunger Up position (minus the Pre-Fill Window). It will continue tomove upon reaching this position until a new command is issued. Themotor 3072 velocity is commanded to move at the calculated DeliveryStroke Velocity. Once the desired position is reached, the MovingThrough Fill Position State is called.

The Moving to Fill Position State commands the motor controller 3430 tomove towards and send a notification upon reaching the Inlet Valve OpenPlunger Up position (plus the Post-Fill Window). It will continue tomove upon reaching this position until a new command is issued. Themotor 3072 velocity is commanded to move at the calculated Refill StrokeVelocity (see Section 8.3). The Refill Stroke Velocity is calculatedupon entering this state prior to issuing a new motor 3072 command.

Once the desired position is reached, the End Deliver State is called.

The End Deliver State checks if the delivery volume has been attained ora stop has been requested. If so, the motor controller 3430 enters theIdle State and the cam shaft 3080 position is commanded to go to theInlet Valve Open Plunger Up position. Otherwise the Start Deliver Stateis called, and a new delivery cycle begins.

The Freeze State is called when the Running State processes a Freezecommand. The cam shaft 3080 position is frozen at its current positionand the Fault Detector and Volume Estimator are notified that thedelivery if frozen.

If a Resume Delivery command is received while in the Freeze State, thestate machine is returned to the state which it was in prior to enteringthe Freeze State. The Fault Detector and Volume Estimator are bothinformed that the delivery is resuming. If a Stop Delivery command isreceived, the Idle State is called.

The Calibration State is the SuperState for the states involved incalibrating the cam shaft 3080 and plunger 3091 positions.

The Finding Home State performs the cam shaft 3080 calibration. Enteringthis state, the IO Access class is notified that a calibration isbeginning so certain sensor protections can be turned off. The statereceives a notification once the process is completed. Upon receivingthis notification, the calibration values are sent to the non-volatilememory. Finally, the Moving to Home State is called.

The Moving to Home State simply commands the peristaltic pump 2990 tomove to the Inlet Valve Open Plunger Up position. Upon reaching thisposition the peristaltic pump 2990 returns to the Idle State.

FIG. 331 rates a possible state chart of the code to detect to detect afault of the peristaltic pump 2990 and FIG. 332 illustrates a occlusiondetection state chart to detect an occlusion of the peristaltic pump2990 in accordance with an embodiment of the present disclosure. FIG. 33shows a feedback control loop to control the speed the peristaltic pump2990 motor 3072 in a peristaltic pump 2990 in accordance with anembodiment of the present disclosure.

Software Architecture

The software architecture of the peristaltic pump 2990 is shownschematically in FIG. 334. The software architecture divides thesoftware into cooperating subsystems that interact to carry out therequired pumping action. The software may be equally applicable to allthe embodiments described herein. The software may also be used forother pump embodiments which may not be described herein. Each subsystemmay be composed of one or more execution streams controlled by theunderlying operating system. Useful terms used in the art includeoperating system, subsystem, process, thread and task.

Asynchronous messages 4130 are used to ‘push’ information to thedestination task or process. The sender process or task does not getconfirmation of message delivery. Data delivered in this manner istypically repetitive in nature. If messages are expected on a consistentschedule, the receiver process or task can detect a failure if a messagedoes not arrive on time.

Synchronous messages 4120 may be used to send a command to a task orprocess, or to request (pull) information from a process or task. Aftersending the command (or request), the originating task or processsuspends execution while awaiting a response. The response may containthe requested information, or may simply acknowledge the receipt of thesent message. If a response is not received in a timely manner, thesending process or task may time out. In such an event the sendingprocess or task may resume execution and/or may signal an errorcondition.

An operating system (OS) is a collection of software that managescomputer hardware resources and provides common services for computerprograms. The operating system acts as an intermediary between programsand the computer hardware. Although some application code is executeddirectly by the hardware, the application code may frequently make asystem call to an OS function or be interrupted by it.

The RTP 3500 runs on a Real Time Operating System (RTOS) that has beencertified to a safety level for medical devices. An RTOS is amultitasking operating system that aims at executing real-timeapplications. Real-time operating systems often use specializedscheduling algorithms so that they can achieve a deterministic nature ofbehavior. The UIP 3600 runs on a Linux operating system. The Linuxoperating system is a Unix-like computer operating system.

A subsystem is a collection of software (and perhaps hardware) assigneda specific set of (related) system functionality. A subsystem hasclearly defined responsibilities and a clearly defined interface toother subsystems. A subsystem is an architectural division of thesoftware that uses one or more processes, threads or tasks.

A process is an independent executable running on a Linux operatingsystem which runs in its own virtual address space. The memorymanagement hardware on the CPU may be used to enforce the integrity andisolation of this memory, by write protecting code-space, anddisallowing data access outside of the process' memory region. Processescan only pass data to other processes using inter-process communicationfacilities.

In Linux, a thread is a separately scheduled, concurrent path of programexecution. On Linux, a thread is always associated with a process (whichmust have at least one thread and can have multiple threads). Threadsshare the same memory space as its ‘parent’ process. Data can bedirectly shared among all of the threads belonging to a process but caremust be taken to properly synchronize access to shared items. Eachthread has an assigned execution priority.

A task on an RTOS (Real Time Operating System) is a separatelyscheduled, concurrent path of program execution, analogous to a Linux‘thread’. All tasks share the same memory address space which consistsof the entire CPU memory map. When using an RTOS that provides memoryprotection, each task's effective memory map is restricted by the MemoryProtection Unit (MPU) hardware to the common code space and the task'sprivate data and stack space.

The processes on the UIP 3600, communicate via IPC calls as shown by theone-way arrows in FIG. 334. Each solid-lined arrow represents asynchronous message 4120 call and response, and dotted-line arrows areasynchronous messages 4130. The tasks on the RTP 3500 similarlycommunicate with each other. The RTP 3500 and UIP 3600 are bridged by anasynchronous serial line 3601, with one of an InterComm Process 4110 orInterComm Task 4210 on each side. The InterComm Process 4110 presentsthe same communications API (Application Programming Interface) on bothsides of the bridge, so all processes and tasks can use the same methodcalls to interact.

The Executive Process 4320 may be invoked by the Linux system startupscripts after all of the operating system services have started. TheExecutive Process 4320 may then start the various executable files thatcomprise the software on the UIP 3600. If any of the software componentsshould exit or fail unexpectedly, the Executive Process 4320 may benotified, and may generate the appropriate alarm.

While the system is running, the Executive Process 4320 may act as asoftware ‘watchdog’ for various system components. After registeringwith the Executive process 4320, a process may be required to ‘check in’or send a signal periodically to the executive process 4320. Failure to‘check in’ at the required interval may be detected by the ExecutiveProcess 4320. Upon detection of a failed subsystem, the ExecutiveProcess 4320 may take remedial action of either: do nothing, declaringan alarm, or restarting the failed process. The remedial action takenmay be predetermined by a table entry compiled into the ExecutiveProcess 4320. The ‘check-in’ interval may vary from process to processbased in part on the importance of the process. The check-in intervalmay also vary during peristaltic pump 2990 operation to optimize thepump controller 4256 response by minimizing computer processes. In oneexample embodiment, during tube loading, the pump controller 4256 maycheck-in less frequently than during active pumping.

In response to the required check-in message, the Executive Process 4320may return various system status items to processes that checked-in. Thesystem status items may be the status of one or more components on thepump and/or errors. The system status items may include: battery status,WiFi connection status, device gateway connection status, device status(Idle, Infusion Running, Diagnostic Mode, Error, Etc.), technical errorindications, and engineering log levels.

A thread running in the Executive Process 4320 may be used to read thestate of the battery 3420 from an internal monitor chip in the battery3420. This may be done at a relatively infrequent interval such as every10 seconds.

The UI View 4330 may implement the graphical user interface (GUI),rendering the display graphics on the display screen 3725, andresponding to inputs on the touch-screen 3735 or other data input means.The UI View 4330 design may be stateless. The screen being displayed maybe commanded by the UI Model process 4340, along with any variable datato be displayed. The commanded display is refreshed periodicallyregardless of data changes.

The style and appearance of user input dialogs (Virtual keyboard, dropdown selection list, check box etc.) may be specified by the screendesign, and implemented entirely by the UI View 4330. User input may becollected by the UI View 4330, and sent to the UI Model 4340 forinterpretation. The UI View 4330 may provide for multi-region,multi-lingual support with facilities for the following list includingbut not limited to: virtual keyboards, unicode strings, loadable fonts,right to left entry, translation facility (loadable translation files),and configurable numbers and date formats.

The UI Model 4340 may implement the screen flows, and so control theuser experience. The US Model 4340 may interact with the UI View 4330,specifying the screen to display, and supply any transient values to bedisplayed on the screen. Here screen refers the image displayed on thephysical display screen 3725 and the defined interactive areas or userdialogs i.e. buttons, sliders, keypads etc, on the touch screen 3735.The UI Model 4340 may interpret any user inputs sent from the UI View4330, and may either update the values on the current screen, command anew screen, or pass the request to the appropriate system service (i.e.‘start pumping’ is passed to the RTP 3500).

When selecting a medication to infuse from the Drug AdministrationLibrary, the UI Model 4340 may interact with the Drug AdministrationLibrary stored in the local data base which may be part of the DatabaseSystem 4350. The user's selections may setup the run time configurationsfor programming and administering the desired medication.

While the operator may be entering an infusion program, the UI Model4340 relays the user's input values to the Infusion Manager 4360 forvalidation and interpretation. Therapeutic decisions may not be made bythe UI Model 4340. The treatment values may be passed from the InfusionManager 4360 to the UI Model 4340 to the UI View 4330 to be displayedfor the user.

The UI Model 4340 may continuously monitor the device status gatheredfrom the Infusion Manager 4360 (current infusion progress, alerts, doorsensor 3163 and slide clamp sensor 3152, etc.) for possible display bythe UI View 4330. Alerts/Alarms and other changes in system state mayprovoke a screen change by the UI Model 4340.

Additional Dosage Safety Software Algorithm(s)

The Infusion Manager Process (IM) 4360 may validate and control theinfusion delivered by the peristaltic pump 2990. To start an infusion,the user may interact with the UI View/Model 4330/4340 to select aspecific medication and clinical use. This specification may select onespecific Drug Administration Library (DAL) entry for use. The IM 4360may load this DAL entry from the database 4350, for use in validatingand running the infusion.

Once a Drug Administration Library entry is selected, the IM 4340 maypass the dose mode, limits for all user enterable parameters, and thedefault values (if set) up to the UI Model 4340. Using this data, the UIModel 4340 may guide the user in entering the infusion program.

As each parameter is entered by the user, the value may be sent from theUI View/Model 4330/4340 to the IM 4360 for verification. The IM 4360 mayecho the parameters back to the UI View/Model 4330/4340, along with anindication of the parameter's conformance to the DAL limits. This mayallow the UI View/Model 4330/4340 to notify the user of any values thatare out of bounds.

When a complete set of valid parameters has been entered, the IM 4360may also return a valid infusion indicator, allowing the UI View/Model4330/4340 to present a ‘Start’ control to the user.

The IM 4360 may simultaneously make the infusion/pump status availableto the UI View/Model 4330/4340 upon request. If the UI View/Model4330/4340 is displaying a ‘status’ screen, it may request this data topopulate it. The data may be a composite of the infusion state, and thepump state.

When requested to run the (valid) infusion, the IM 4360 may pass the‘Infusion Worksheet’ containing user specified data and the ‘InfusionTemplate’ containing the read-only limits from the DAL as a CRC'd binaryblock to the Infusion Control Task 4220 running on the RTP 3500. TheInfusion Control Task 4220 on the RTP 3500 may take the same userinputs, conversions and DERS inputs and recalculate the InfusionWorksheet. The Infusion Control Task 4220 calculated results may bestored in a second CRC'd binary block and compared to the first binaryblock from the UIP 3600. The infusion calculations performed on the UIP3600 may be recalculated and double checked on the RTP 3500 before theinfusion is run.

Coefficients to convert the input values (i.e. □l, grams, %) to astandard unit such as ml may be stored in the UIP 3600 memory ordatabase system 4350. The coefficients may be stored in a lookup tableor at specific memory locations. The lookup table may contain 10's ofconversion values. In order to reduce the chance that flipping a singlebit will resulting in the wrong conversion factor being used, theaddresses for the conversion values may be distributed among the valuesfrom zero to 4294967296 or 2³². The addresses may be selected so thatthe binary form of one address is never just one bit different from asecond address.

While an infusion is running, the IM 4360 may monitor its progress,sequences, pauses, restarts, secondary infusions, boluses and KVO (keepvein open) scenarios as needed. Any user alerts requested during theinfusion (Infusion near complete, KVO callback, Secondary completecallback, etc) may be tracked and triggered by the IM 4360.

Processes on the UIP 3600 may communicate with each other via aproprietary messaging scheme based on a message queue library that isavailable with Linux. The system may provide for both acknowledged(synchronous message 4120) and unacknowledged (asynchronous message4130) message passing.

Messages destined for the Real-time Processor (RTP) 3500 may be passedto the InterComm Process 4310 which may forward the messages to the RTP3500 over a serial link 3601. A similar InterComm Task 4210 on the RTP3500 may relay the message to its intended destination via the RTP 3500messaging system.

The messaging scheme used on this serial link 3601 may provide for errordetection and retransmission of flawed messages. This may be needed toallow the system to be less susceptible to electrical disturbances thatmay occasionally ‘garble’ inter-processor communications.

To maintain a consistent interface across all tasks, the messagepayloads used with the messaging system may be data classes derived froma common baseclass (MessageBase). This class adds both data identity(message type) and data integrity (CRC) to messages.

The Audio Server Process 4370 may be used to render sounds on thesystem. All user feedback sounds (key press beeps) and alarm or alerttones may be produced by playing pre-recorded sound files. The soundsystem may also be used to play music or speech if desired.

Sound requests may be symbolic (such as “Play High Priority AlarmSound”), with the actual sound file selection built into the AudioServer process 4370. The ability to switch to an alternative soundscapemay be provided. This ability may be used to customize the sounds forregional or linguistic differences.

The Device Gateway Communication Manager Process (DGCM) 4380 may managecommunications with the Device Gateway Server over a Wi-Fi network 3620,3622,3720. The DGCM 4380 may be started and monitored by the ExecutiveProcess 4320. If the DGCM 4380 exits unexpectedly, it may be restartedby the Executive Process 4320 but if the failures are persistent thesystem may continue to function without the gateway running.

It may be the function of the DGCM 4380 to establish and maintain theWi-Fi connection and to then establish a connection to the DeviceGateway. All interactions between the DGCM 4380 and the Device Gatewaymay system such as the system described in the cross-referencednonprovisional application for System, Method, and Apparatus forElectronic Patient Care (Attorney Docket No. J85).

If the connection to the gateway is unavailable or becomes unavailable,the DGCM 4380 may discontinue any transfers in progress, and attempt toreconnect the link. Transfers may be resumed when the link isreestablished. Network and Gateway operational states may be reportedperiodically to the Executive Process 4320. The Executive Process 4320may distribute this information for display to the user.

The DGCM 4380 may function as an autonomous subsystem, polling theDevice Gateway Server for updates, and downloading newer items whenavailable. In addition the DGCM 4380 may monitor the logging tables inthe database, uploading new log events as soon as they are available.Events that are successfully uploaded may be flagged as such in thedatabase. After a reconnection to the Device Gateway Server, the DGCM4380 may ‘catch up’ with the log uploads, sending all items that wereentered during the communications disruption. Firmware and DrugAdministration Library updates received from the Gateway may be stagedin the UIP's 3600 file system for subsequent installation. Infusionprograms, clinical advisories, patient identification and other dataitems destined for the device may be staged in the database.

The DGCM 4380 may report connection status and date/time updates to theExecutive Process 4320. There may be no other direct connections betweenthe DGCM 4380 and any of the other operational software. Such a designdecouples the operational software from the potentially transientavailability of the Device Gateway and Wi-Fi network.

The Motor Check 4383 software reads a hardware counter or encoder 3438(FIG. 325) that reports motor 3072 rotation. The software in this moduleindependently estimates the motor's 3072 movements, and compares them tothe expected motion based on the user inputs for rate of infusion. Thisis an independent check for proper motor control. However, the primarymotor control software may be executed on the RTP 3500.

Event information may be written to a log via the Logging Process 4386during normal operation. These events may consist of internal machinestatus and measurements, as well as therapy history events. Due to thevolume and frequency of event log data, these logging operations may bebuffered in a FIFO queue while waiting to be written to the database.

A SQL database (PostgreSQL) may be used to store the Drug AdministrationLibrary, Local Machine Settings, Infusion History and Machine Log data.Stored procedures executed by the database server may be used toinsulate the application from the internal database structures.

The database system 4350 may be used as a buffer for log data destinedfor the Device Gateway server, as well as a staging area for infusionsettings and warnings sent to the pump from the Gateway.

Upon requesting the start of an infusion, the DAL entry and all userselected parameters may be sent to the Infusion Control Task 4220. Allof the DAL validations and a recalculation of the infusion rate andvolume based upon the requested dose may be performed. The result may bechecked against the results calculated by the IM 4360 on the UIP 3600.These results may be required to match to continue.

When running an infusion, the Infusion Control Task 4220 may control thedelivery of each infusion ‘segment’; i.e. one part of an infusionconsisting of a volume and a rate. Examples of segments are: a primaryinfusion, KVO, bolus, remainder of primary after bolus, primary aftertitration, etc.

The infusion segments are sequenced by the IM Process 4360 on the UIP3600.

The Pump Control task 4250 may incorporate the controllers that drivethe pumping mechanism. The desired pumping rate and amount (VTBI) may bespecified in commands sent from the Infusion Control Task 4220.

The Pump Control 4250 may receive periodic sensor readings from theSensor Task 4264. The new sensor readings may be used to determine themotor 3072 speed and position, and to calculate the desired command tosend to the Brushless Motor Control IRQ 4262. The receipt of the sensormessage may trigger a recalculation of the controller output.

While pumping fluid, the Pump Control Task 4250 may perform at least oneof the following tasks: controlling pumping speed, measuring volumedelivered, measuring air detected (over a rolling time window),measuring fluid pressure or other indications of occlusions, anddetecting upstream occlusions.

Relevant measurements may be reported to the RTP Status Task 4230periodically. The Pump Control 4250 may execute one infusion segment ata time, stopping when the commanded delivery volume has been reached.The Sensor Task 4264 may read and aggregate the sensor data used for thedynamic control of the pumping system. The sensor data may include therotary encoder 3130 measuring the cam-shaft, the linear encoders 3520,3525 measuring the position of the plunger 3091.

The sensor task 4264 may be scheduled to run at a consistent 1 kHz rate(every 1.0 ms) via a dedicated counter/timer. After all of the relevantsensors are read, the data may be passed to the Pump Control Task 4250via an asynchronous message 4120. The periodic receipt of this messagemay be used as the master time base to synchronize the peristalticpump's 2990 control loops.

The RTP Status Task 4230 may be the central repository for both thestate and the status of the various tasks running on the RTP 3500. TheRTP Status Task 4230 may distribute this information to both the IM 4360running on the UIP 3600, as well as to tasks on the RTP 3500 itself.

The RTP Status Task 4230 may also be charged with fluid accounting forthe ongoing infusion. Pump starts and stops, as well as pumping progressmay be reported to RTP Status 4230 by the Pump Control Task 4256. TheRTP Status Task 4230 may account for at least one of the following:total volume infused, primary volume delivered, primary VTBI (counteddown), volume delivered and VTBI of a bolus while the bolus is inprogress, and volume delivered and VTBI of a secondary infusion whilethe secondary infusion is in progress.

All alerts or alarms originating on the RTP 3500 may be funneled throughthe RTP Status Task 4230, and subsequently passed up to the UIP 3600.

While the unit is in operation, the program flash, and RAM memory may becontinually tested by the Memory Checker Task 4240. This non-destructivetest may be scheduled so that the entire memory space on the RTP 3500 istested every few hours. Additional periodic checks may be scheduledunder this task if needed.

Tasks running on the RTP 3500 may be required to communicate with eachother as well as to tasks that are executing on the UIP 3600.

The RTP messaging system may use a unified global addressing scheme toallow messages to be passed to any task in the system. Local messagesmay be passed in memory utilizing the facilities of the RTOS' messagepassing, with off-chip messages routed over the (asynchronous serial3601) communications link by the InterComm Task 4210.

The InterComm Task 4210 may manage the RTP 3500 side of the serial link3601 between the two processors. It is the RTP 3500 equivalent of theInterComm Process 4310 on the UIP 3600. Messages received from the UIP3600 may be relayed to their destination on the RTP 3500. Outboundmessages may be forwarded to InterComm Process 4310 on the UIP 3600.

All messages between the RTP 3500 and the UIP 3600 may be checked fordata corruption using an error-detecting code (32 bit CRC). Messagessent over the serial link 3601 may be re-sent if corruption is detected.This provides a communications system that may be reasonably tolerant toESD. Corrupted messages within the processor between processes may behandled as a hard system failure. All of the message payloads used withthe messaging system may be data classes derived from a common baseclass(MessageBase) to assure consistency across all possible messagedestinations.

Brushless Motor control 4262 may not run as a task; it may beimplemented as a strict foreground (interrupt context) process.Interrupts may be generated from the commutator or hall sensors 3436,and the commutation algorithm may be run entirely in the interruptservice routine.

FIGS. 335 and 336 illustrate the geometry of two dual-band antennas thatmay be used with the peristaltic pump 2990 in accordance with anembodiment of the present disclosure. FIG. 335 shows a top and a bottomview of the antenna, which may be fabricated using metallic layers on asubstrate, such as is typically made when manufacturing a printedcircuit board. FIG. 336 may also be fabricated using a printed circuitboard manufacturing method.

Various alternatives and modifications can be devised by those skilledin the art without departing from the disclosure. Accordingly, thepresent disclosure is intended to embrace all such alternatives,modifications and variances. Additionally, while several embodiments ofthe present disclosure have been shown in the drawings and/or discussedherein, it is not intended that the disclosure be limited thereto, as itis intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. And, those skilled in theart will envision other modifications within the scope and spirit of theclaims appended hereto. Other elements, steps, methods and techniquesthat are insubstantially different from those described above and/or inthe appended claims are also intended to be within the scope of thedisclosure.

The embodiments shown in the drawings are presented only to demonstratecertain examples of the disclosure. And, the drawings described are onlyillustrative and are non-limiting. In the drawings, for illustrativepurposes, the size of some of the elements may be exaggerated and notdrawn to a particular scale. Additionally, elements shown within thedrawings that have the same numbers may be identical elements or may besimilar elements, depending on the context.

Where the term “comprising” is used in the present description andclaims, it does not exclude other elements or steps. Where an indefiniteor definite article is used when referring to a singular noun, e.g.,“a,” “an,” or “the,” this includes a plural of that noun unlesssomething otherwise is specifically stated. Hence, the term “comprising”should not be interpreted as being restricted to the items listedthereafter; it does not exclude other elements or steps, and so thescope of the expression “a device comprising items A and B” should notbe limited to devices consisting only of components A and B. Thisexpression signifies that, with respect to the present disclosure, theonly relevant components of the device are A and B.

Furthermore, the terms “first,” “second,” “third,” and the like, whetherused in the description or in the claims, are provided fordistinguishing between similar elements and not necessarily fordescribing a sequential or chronological order. It is to be understoodthat the terms so used are interchangeable under appropriatecircumstances (unless clearly disclosed otherwise) and that theembodiments of the disclosure described herein are capable of operationin other sequences and/or arrangements than are described or illustratedherein.

What is claimed is:
 1. A peristaltic pump for pumping fluid in aplurality of cycles where each cycle has at least first, second, andthird stages, the peristaltic pump comprising: a plunger configured toactuate toward and away from a tube; an inlet valve upstream of theplunger; an outlet valve downstream of the plunger; a spring configuredto bias the plunger toward the tube; and an actuator configured tomechanically engage and disengage from the plunger, wherein: in thefirst stage, the inlet valve is opened and the plunger is actuated fromthe tube, in the second stage, the inlet valve is closed, the plunger isactuated toward the tube, and the actuator is mechanically disengagedfrom the plunger, in the third stage, the outlet valve is opened, and inthe third stage or in a fourth stage, the actuator actuates the plungertoward the tube to discharge fluid downstream past the outlet valve. 2.The peristaltic pump according to claim 1, wherein in the third stage,the outlet valve is opened and the actuator actuates the plunger towardthe tube to discharge fluid downstream past the outlet valve.
 3. Theperistaltic pump according to claim 1 or 2, wherein in the first stage,the outlet valve is closed.
 4. The peristaltic pump according to claim 1or 2, wherein the actuator includes a cam and the plunger is coupled toa cam follower configured to follow the cam.
 5. The peristaltic pumpaccording to claim 4, wherein when the actuator mechanically engageswith the plunger, the cam follower follows the cam.
 6. The peristalticpump according to claim 4, wherein when the actuator mechanicallyengages with the plunger, the cam follower and the cam are in physicalcontact with each other.
 7. The peristaltic pump according to claim 4,wherein when the actuator is mechanically disengaged with the plunger,the cam follower does not follow the cam.
 8. The peristaltic pumpaccording to claim 4, wherein when the actuator is mechanicallydisengaged with the plunger, the cam follower and the cam are not inphysical contact with each other.
 9. The peristaltic pump according toclaim 1 or 2, wherein in each cycle of the peristaltic pump, the firststage occurs prior to the second stage and the second stage occurs priorto the third stage.
 10. The peristaltic pump according to claim 1 or 2,wherein the actuator, the spring, and the plunger are configured tocharge the spring when the actuator actuates the plunger away from thetube.
 11. The peristaltic pump according to claim 1 or 2, wherein theactuator, spring, and plunger are configured to discharge the springwhen the actuator mechanically disengages from the plunger.
 12. Theperistaltic pump according to claim 1 or 2, wherein the actuator isconfigured to mechanically disengage from the plunger to therebydischarge the spring to bias the plunger against the tube.
 13. Theperistaltic pump according to claim 1 or 2, wherein actuation of theactuator does not correspond to actuation of the plunger when theactuator mechanically disengages from the plunger.
 14. The peristalticpump according to claim 1 or 2, wherein the actuator is configured tonot contribute to a force of the plunger against the tube.
 15. Theperistaltic pump according to claim 1 or 2, wherein the actuator isconfigured to mechanically engage the plunger to lift the plunger awayfrom the tube and mechanically disengage the plunger to allow the springto generate a force from the plunger against the tube.
 16. Theperistaltic pump according to claim 1 or 2, wherein the peristaltic pumpis configured such that a force of the plunger applied to the tube bythe plunger is produced by the spring and not the actuator.
 17. Aperistaltic pump according to claim 1, for pumping fluid in a pluralityof cycles where each cycle has first, second, third, and fourth stages,wherein: in the first stage, the inlet valve is opened and the plungeris actuated from the tube, in the second stage, the inlet valve isclosed, the plunger is actuated toward the tube, and the actuator ismechanically disengaged from the plunger, in the third stage, theactuator is mechanically engaged with the plunger, the actuator actuatesthe plunger away from the tube, and the outlet valve is opened, and inthe fourth stage, the actuator actuates the plunger toward the tube todischarge fluid downstream past the outlet valve.
 18. The peristalticpump according to claim 17, wherein in the first stage, the outlet valveis closed.
 19. The peristaltic pump according to claim 17, wherein theactuator includes a cam and the plunger is coupled to a cam followerconfigured to follow the cam.
 20. The peristaltic pump according toclaim 19, wherein when the actuator mechanically engages with theplunger, the cam follower follows the cam.
 21. The peristaltic pumpaccording to claim 19, wherein when the actuator mechanically engageswith the plunger, the cam follower and the cam are in physical contactwith each other.
 22. The peristaltic pump according to claim 19, whereinwhen the actuator is mechanically disengaged with the plunger, the camfollower does not follow the cam.
 23. The peristaltic pump according toclaim 19, wherein when the actuator is mechanically disengaged with theplunger, the cam follower and the cam are not in physical contact witheach other.
 24. The peristaltic pump according to claim 17, wherein ineach cycle of the peristaltic pump, the first stage occurs prior to thesecond stage, the second stage occurs prior to the third stage, and thethird stage occurs prior to the fourth stage.
 25. The peristaltic pumpaccording to claim 17, wherein the actuator, the spring, and the plungerare configured to charge the spring when the actuator actuates theplunger away from the tube.
 26. The peristaltic pump according to claim17, wherein the actuator, spring, and plunger are configured todischarge the spring when the actuator mechanically disengages from theplunger.
 27. The peristaltic pump according to claim 17, wherein theactuator is configured to mechanically disengage from the plunger tothereby discharge the spring to bias the plunger against the tube. 28.The peristaltic pump according to claim 17, wherein actuation of theactuator does not correspond to actuation of the plunger when theactuator mechanically disengages from the plunger.
 29. The peristalticpump according to claim 17, wherein the actuator is configured to notcontribute to a force of the plunger against the tube.
 30. Theperistaltic pump according to claim 17, wherein the actuator isconfigured to mechanically engage the plunger to lift the plunger awayfrom the tube and mechanically disengage the plunger to allow the springto generate a force from the plunger against the tube.
 31. Theperistaltic pump according to claim 17, wherein the peristaltic pump isconfigured such that a force of the plunger applied to the tube by theplunger is produced by the spring and not the actuator.